I went ahead and bought the 3 Gravis gamepads for $9.99 deal, despite some ugly reviews I read on the net.
Install was a bit of a headache, seems like I had to do it a few times to get it working, but now they work fine, at least for my purposes. I'm hoping they turn out to be hackable, but even if they don't, I've been meaning to get some some el-cheap-o dual analog gamepads for Mutant Storm anyway, and I just played my best game ever.
Thanks, Mr. Troy.