i dont own a mpc but as far as i know, sampletank will work in cubase. I dont really understand your delima tho the way you originally quoted it. I use flstudio as my secquencer but isn't that what you bought the mpc for?
what exactly are you trying to do with sampletank? play multiipal sounds in 1 sample tank in the different parts or play different patterns?
in the sample tank xl user manual i believe its page 37 or something close to that that explaing the using of PARTS on different midi channels so you can use 1 sample tank and trigger bultipal sounds as long as you can set triggers to different channelsfor when programming notes.
but then again i dont understand what your trying to do