I have created a PortableApps.com Format launcher for Game Maker 8.
It can be downloaded here http://www.box.net/shared/7hiqcx9kry
Please note that this package does not include the atuall Game Maker 8 files.
To use this with game Maker 8, follow these steps.
1) Us the above PortableApps.com Installer
2) Download and install Game Maker 8
3) Go to the directory where you installed it, highlight all the files by click&drag
4) Right-click>>copy those files, then go to the following folder and right-click>>paste once you are there
YourDrive:\PortableApps\GameMaker8\App\Game_Maker8
Once you have done all this you now have a portable version of Game Maker 8
The archive provided above DOES NOT CONTAIN ANY ORIGIANAL YOYOGAMES CONTENT BESIDES THE ICON
EDIT:
Pack now comes in PortableApps.com Format Installer exe.
Now I can guaranty that the pro version is NOT portable