Umm...well...in your thread title you did ask how to put a poser mesh into bryce. That does require you to firstly get the mesh out of poser. Anyway, if you don't want to go with poser, but still want a figure you can pose into a sitting person shape, twistedbolt (I think) made a human figure for use in bryce. I'm not sure where it is, but it may give you a bryce only option (just get in touch with him).

Dreams are just nightmares on prozac...
Digital WasteLanD