No prob...a couple of notes there, tho...
The key piece isn't going to be the sound-producing parts. Actually, the real key here is the sequencer. Make sure that, since you're going to vary the groove you want, that this module has an easy to work 'on the fly' interface, and that whatever you wind up with has settings (or some additional modules) that can suitably 'humanize' the results. I know that quite a few producers who made use of the Roland TR-909 really relied on its 'swing' settings to add some 'slippage' to an otherwise-metronomic pattern. Plus, when you locked it to something that didn't have that feature, you'd get some really excellent flam behavior as the two machines would be a tad out of sync on that particular beat. Adding something that can also add a random change-up to one or two channels of triggers (Ladik has an inexpensive 2-channel probabilistic skipper) will do a lot to add some humanization when you keep the probability settings kind of low so that the skips sound a bit like on the fly change-ups.
Sound-wise, while you'll definitely want some of the 'standards' (808 or 909 kicks, 909 or 606 hats, etc etc), keep in mind that a lot (like...all?) of the classic beatbox sounds and such are done with 'ringing filters' to a great extent. Basically, the sounds are produced with fixed-frequency filters that are set to just a touch under resonance, and then triggered with either an envelope that determines the overall duration of the sound (like a triggered decay or an AD envelope with a sharp attack) or a quick pulse of sound that pops the filter into resonance for an instant.
Since in a modular, though, you don't have to deal with fixed-frequency filters, it's possible to not only trigger the filter however you like, you can also send the same triggers to a CV sequencer, then get a 'melody' of sorts as the sequencer changes the cutoff of the filter. Very 'rototom-ish' sort of behavior (think: opening of Pink Floyd's "Time"). Also, mixing on this sort of a device should be pretty simple; look at MFB's Drum-99 mixer, which is a basic stereo mixer which you can chain to another one, etc, and build up a drum bus where you have relatively fixed levels and pans.
Another great, gnarlier (is that even a word?) sound can be done by sending various colored noise bands thru exponential VCAs and controlling their levels with, again, fast, snappy AD or decay envelopes. This is good for cymbals, snares, and the like. Plus, with noise-based sounds you then have this great ability to sum those and then do a little more filter-sweepy stuff, make 'em sound sort of dubby-trippy.
Loads of possibilities...that's just a few.