You could try this,
Intall to th c drive, but where you get an option to install certain items somewhere else, then choose the d drive for those things.
For example load all content and wave files etc to d drive, as they take up the most space.
That way the brains of x2 will be on the os drive, but all the referenced materials and files will be on the d drive.
I beleive this is actually preferable as it should work more efficiently.
Also, 'a must do' is to change the location of the audio folder to another drive from C.
Thi speeds up peformance, as windows and programs access C drive and Audio is written to a seperate drive while recording.
On my machine, although i specified my E drive as the audio drive in preferences (press P) i still have to change the audio folder drive letter to E when saving a project.
Wen saving a project i make a new folder with the song name to save to, and underneath that box where it asks where to store audio file i simply change the drive letter to E, and then make sure the same song name folder is added to the end of the string.
Eg
G\x2projects\bluesuedeshoes
E\x2projects\audio\bluesuedeshoes
Hope this helps and sorry if you already knew this stuff