I vaguely recall reading somewhere cyclists performing plyometrics similar to that of ice skaters, ie: lots of single leg stuff, bow jumps, stair bounds etc BUT 1) this wasn't a study so the results cannot be quantified and 2) was during the offseason in the depths of winter.
There was also a study done with plyos being worked in with cycling sprints to some favorable result (IIRC), if I can find I will link.
My personal experience is that a solid ergo (or spin bike even), a fan, a bucket and crash mat will serve all your sprinting needs if you can't do it outside.