If I understand your question,your Rotel is a stereo amp--2 channels, left and right. You could use one of those two channels to drive a center-channel speaker, or you could drive the M60i's as front left and right main channels. But you need an outboard Dolby Digital or Pro Logic decoder to derive a center-channel signal from Dolby Surround tapes, DVDs or CDs, and an additional mono amp to drive the center channel. Technics used to offer an inexpensive outboard Dolby Digital/dts decoder, but you'll still need 3 extra amps for the center and two surround channels.
You might find a used Pro Logic decoder on ebay; Yamaha used to build some with ProLogic decoder and three internal amps built in to power the center channel and 2 surround channels. They were intended for people like you, who only had a simple stereo amp and wanted to upgrade to 5-channel home theater. You could use the Rotel to drive the main front left and right channel M60i's.
Axiom Resident Expert