I have a similar Alienware Laptop too. Such a pain in the butt those things are. My configuration has the staked ontop of eachother which is useless. They get too hot for normal use, So now I use one drive for OS and the other for backups via Veritas.
Even though it sucks, I would take you time and install one drive at a time in the chasis. You should be able to Identify which on is master by how it boots up. I don't think the controler can idenitfy cable select, and wont function of the the raid controler is disabled. ( for some reason it says my is sata? highpriced crap)But check it out, but be careful, that 2 inch HDR is very delicate. And with Dell's aquistion of Alienware, oem parts will be hard to come by.