Did you get my PM?
The softmod author decided which partition and filename to boot from when he/she made the softmod, and you can't change it - that's why you have to know which softmod it is, or work out for yourself which partition/filename the softmod looks for as its first dash. Later versions of SID use E:\evoxdash.xbe. To replace the dash you replace evoxdash.xbe with your preferred dash, which you have to rename evoxdash.xbe. You also have to put the config file (config.xml for UnleashX, evox.ini for evox) in the same place i.e. the root of the e partition. But let me stress again, different versions of SID can put the dash in different places, so you need to do a bit of detective work before you start. The fact that XBMC is on E isn't necessarily an indication of where the Xbox is booting its dash from - it could be set up with the dash on C, but with the XBMC shortcut as the dash (which then loads XBMC from E).
Whatever you do, don't touch ANYTHING on the C partition until you are certain that you know what you are doing, because it's files on the C partition that trigger the softmod.
And don't use AID - it's designed primarily for chipped Xboxes. I suspect that it might work if your softmod is SID 5.1, but equally it might fail spectacularly for older versions.