It's pretty common, for guys who're decent and looking for that kinda thing. One way to do it is funnel screening. Something like, (1) broadcast your intent by being loud, sexual, and rambunctious (think Austin Powers or Owen Cook), (2) you or a wing scan the room for eye contact or attention, (3) invade her space or privacy early, then walk away (like pulling a ponytail, NOT like grabbing her inappropriately. intense eye contact + a wink works, too). A girl who's interested in sexual escalation will get your attention without more from you, maybe she'll even self-isolate. After that, you'll want to lean back and take her wrist below her waist. Escalate verbally before physically (often this works best bc words have the same arousing effect as touch, but w/out some of the hazards).
If she likes it when you talk about that kinda touching, she's likely to accept your actually doing it.
So, Broadcast, ID, quick intense flirtation, walk away, wait, touch, talk, (ask, probably), then try.
That'd be one way to go about it.