You'd need a weird piece of furniture to support you properly to do all that with your hands that busy!
I've made girls cum from sex while sucking on their nipples plenty of times (missionary position works here).
I've made girls cum from sex with a finger in their butts plenty of times too (doggy style / rear entry works).
Less often, I've made girls cum with a finger in their butts and a hand fondling their tits (doggy style). At this point though you have no free hand to support yourself and the position is pretty awkward. Best way to do it is to hold off on the titty-grabbing until she is very close to cumming, then give those titties a big ol' squeeze right as she's about to climax, and really send her over the edge (you can have your finger in her butt the whole time).
I cannot imagine what kind of contortions you'd have to twist yourself into to dick a girl down, while rubbing her clit, while fingerbanging her in the stink, while sucking on her titties, though. I guess doable in theory?
I will say though, these weird contortionist positions can be very exciting for the girl, but they are generally less enjoyable for you.
So, nice to do on occasion to send girls over the edge, but not a thing you will want to be doing regularly.
(Even just having a thumb in her butt limits you... you cannot really thrust as hard or as deep, and you will be able to feel your thumb in there with your cock, too. Makes me wonder how the dudes doing MFM threesomes do it... I can't imagine you wouldn't be smashing that dude's cock from the other side of the abdominal wall. Maybe that's all part of the bonding experience though?)
-C
