There isn't much to roleplaying really - the basic idea is that person A (usually the dominating party) ignites an action by describing the setting and how the character(s) in it are acting, then person B (usually the submissive party) reacts to what happens. A good submissive/victim roleplayer will not only re-describe the words of his partner though. He will try to offer more ideas, more plot hooks, invite and suggest options that the dominating partner might pick up at his leisure. It is a ping pong match with words where no party is interested in winning, but instead in having a great match for the camera!
My shortest roleplay took two poses. My longest roleplay lasted for 12 months. The only limit to roleplaying is the creativity of the partners.
This here
viewtopic.php?f=5&t=875 is probably a good blueprint for how roleplaying can function. It has a well crafted out background, quite a few characters and a strong line of action. Diablo started, I replied, then it went Diablo, Ahastar, Diablo, Ahastar and so on. This happened via messanger, too. A fully shapeable environment like Faibanx can help with roleplaying because you can actually physically create a background - but so can your fantasy and creativity! I have always been of the opinion that a bit of chatting and planning before actually playing helps a lot to get what you want, too.