Hi Lee Ann -
You should be able to install on a different drive. Just add the worker in with the "Add" button vs. using "Discover".
The only potential gotcha that you should be aware of is if you're using SSL. The SSL cert must be placed in the exact same location on the workers as on your primary:
Doing so COULD be problematic if you do something like install the Primary Server on a D: drive and place your SSL cert on D: ....and then attempt to install your workers on boxes which only have a C: drive -- you'd have no way to place your SSL cert in D: like you need to.