Unplug all other disk and install win8. Make sure the ssd is your first boot device an reconnect all other disk now. Win8 will boot from the ssd and you will see all other disk, move the data around, format them or do whatever you want.
+1. This is the best method to ensure that Windows 8 installs on the disk you want, and doesn't do something stupid like put the recovery environment partition on another disk (I have seen this before and it's caused me a few headaches).