[Welcome to all our visitors arriving from the blogosphere. It's mentioned below, but it really should be step 0, so let me save a bunch of you some time and frustration: This process requires a modded PS2 capable of playing burned DVDs. This is NOT something we will assist you with here. If that's you, then feel free to continue reading. If not, thanks for stopping by, and if you enjoy Guitar Hero, do take a look around the rest of our site. 
--The Management]
It should be idiot proof, because i can do it 
I decided to do this because there is some incredible work going on and peoples creations deserve to be played, so i thought a simple one stop guide would encourage more people to try it out.
I’m going to attempt to write this guide so that the level of prior knowledge required is zero. So forgive me if you read this and think a lot of stuff is obvious.
Firstly let me state this guide will only help you with getting other peoples created songs into your Guitar Hero 2 game
It Contains no information on creating custom notecharts.
Tools Needed (All programs are freeware) Use “paddy” without the quotes if the .rar asks for a password.
Guitar Hero Explorer: http://scorehero.com/forum/viewtopic.php?t=2549
GHero Utils: http://scorehero.com/forum/viewtopic.php?t=2132
Audacity: http://audacity.sourceforge.net/
MFAudio: http://www.zophar.net/utilities/ps2util.html
Anvil Studio: http://www.anvilstudio.com/
CD-DVD Generator: http://utilities.psxforum.com/cddvdgen.zip
Apache: http://www.ps3news.com/forums/downloads.php?do=file&id=9
DVD Decrypter/Nero/Alcohol/Any other ISO burning software.
Swap Magic/Mod Chip/Method of booting burns on your PS2 (If you don’t have one, don’t ask, you wont be getting any help)
A DVD Burner
Good quality media to burn to. This is REALLY REALLY REALLY important. If your eventual burn does not work, this is the number one reason why. I recommend Taiyo Yuden, Sony and Verbatim or Check: http://www.digitalfaq.com/media/dvdmedia.htm for a full list
The Actual Process
Step 1. Download the provided .mid file
Step 2. Check to see if the .mid is for GH2 and not GH1, if this is not made clear by the person who posted it, check the video link if there’s one provided, or ask them
Step 3. If the .mid is for GH1, or you are unsure, open Anvil Studio, load up your .mid. Look at the yellow box near the top, if it says “PART GUITAR” leave it, if not, right click it and make it so. Now go to View –> Event List, select “Events” from the drop down menu and scroll down to the bottom. Look for the entry with “Comments: [end]“. If there are brackets around the word end you’re good to go, if there aren’t, double click the entry and put them in.
Step 4. Get an .mp3 of the song in question. If one is freely available, it may have been provided by the song creator, if not you will need to rip it from the CD or buy it from Itunes.
Step 5. Insert your GH2 disc into your DVD drive, copy the contents of the disc to a folder on your hard drive.
Step 6. Open Guitar Hero Explorer (Ghex), Go to file —> add archive and locate your MAIN.HDR file which is in the “GEN” folder you copied from the GH2 disc
Step 7. In Ghex expand “Songs” and then the song you wish to replace, right click on the .mid file for that song and hit replace, now locate the .mid of your custom song and hit replace.
Step 8. Right click the .vgs file of the same song and click import, now right click the new box and select Add. Find your mp3 from step 4 and just fill in the bottom with the default settings. After it has finished you can preview your vgs by hitting play to check it’s worked.
Step 9. Click on the folder for the song you replaced, you should see a preview of your note chart, click play, slow the playback down to 50% and check your audio file does not start too late or too early, if it does, go back to step 8 but after adding your mp3, right click it and select properties. Now fiddle around with the offset (+ if the song starts too early, – if it starts too late) and import it again. Repeat until you get it right.
Alternatively, if you have problems with GHEX (as the VGS feature is still in its early life) you can use the original method
Code:
Open your .mp3 with audacity and go to File —> Export as WAV
Open MFAudio, select your new WAV as the input file and select .vag as your output format. Now hit process
Unzip the contents of the GhUtils archive to a folder called “GHUtils” in your Program Files folder. Open command prompt (Start Menu —> Run —> cmd) locate the folder to which you unzipped GHutils (type cd \Program Files\GHUtils) and type java FileExpandGuitarHero
This will launch the vgs converter. Find your .vag from step 6 and hit New Audio. When it’s done it will ask you to enter a hex value, just ignore it and hit cancel. You now have everything you need to play your song, now to get them in the game 
Step 10. That’s all the file swapping done, now to rebuild the game. Open CD/DVD Generator, select new project and then New DVD Master disc, drag and drop the folders and files from the GH2 game disc into the main window in the following order.
GEN
IOP
VIDEOS
SLUS_214.47 (If you are not using the US version of the game this file will be different)
System
Now click on the “Volume” tab and enter SLUS 21447 (or whatever your file said if it was different) into the “Disc Name” field. Put PLAYSTATION in the “Producer Name” field and change the license area to the appropriate region. Ignore the rest. Now click on File —> Export .iml file
Step 11: Open Apache, Go to File —> Create —> ISO from IML file, select the IML you made in the previous step and let it do it’s thing.
Step 12: Open up DVD Decrypter/Nero/Alcohol/Your burning program of choice and burn your ISO at 4x to GOOD QUALITY MEDIA (see above)
That’s it, you’re done. That may look like a long process, but once you have the procedure down it doesn’t take much longer than 10-15 minutes including wait times to get the ISO.
Let me know if i’ve missed anything or if anything is wrong. (I’m not sure about the changing GH1 midi to GH2, can someone confirm that what i said in step 3 is all that’s needed as i haven’t tried it myself yet.)[/code]
Source: ScoreHero.com :: View topic - Idiot Proof Guide to playing custom made songs in GH2.
