Okay, a friend of mine was asking me how to do this. He has Morrowind for his PC and his Xbox. He's wanting to use his Action Replay to move his PC save to his Xbox. His Xbox hasn't been modded in any way at all.

You need to first put the save in a format action replay recognizes (this involves making a datel.xbx text file describing the save, you can pull this from another action replay save file), and you need to add a vv.dat file with a calculated checksum of the savefile stored in binary. The second part takes a bit more work, you have to calculate this with a program called XSavSig and then create the vv.dat file with a hex editor.