I've been wanting to do that too for about a year now. I know just like the author of this thread probally knew that DVD2Xbox can copy the games to F:/Game directory but i want to use PxHddLoader instead. It has a features that DVD2Xbox doesn't have such as displaying the free space of your hardrive. I've used CXBX 0.7.8c to extract the hddloader.xbe into a Win32 .exe and was able to open it in W32Dasm V8.9 but i didn't see any paths in the disassambled .exe but only code.
I created the HDDLoader.ini file and changed the path to F:/Games but that does't work either. The optional .ini file was only added for people who run the debug dashboards.
Quote for readme.txt:
6) Reads HDDLoader.ini file to parse for a new path, for all
you Debug Kit owners, you can now create HDDLoader.ini with
the following in it:
[Newpath]
path = "\Device\Harddisk0\Partition1\devkit"
And it will read that folder for PxGame* for games, so you
can easily Launch them from the XDK Launcher screen.
Anyone out there know how to change the .xbe to see F:/Games instead of F:/HDDLoader ?