Try using a plugin called pulse3d which does realtime rendering on teh fly with full mesh deformation.
http://www.pulse3d.com

However, the way you would do character animation in flash at present if you don't want it to be realtime rendering, then you just use illustrate 4.1 or vecta 3d, you simply export the whole lot as an series of swf's rather than a series of 3ds. this is how titoonic did it as far as i know. they are set clips which were animated in 3d adn rendered out as swf. and the interactivity is planned and has set clips which are triggered.
they aren'y generated on teh fly like metastream, or pulse.