On the cloth room.
Yes you can use conforming in the cloth room to expand them. => See the Poser manual

And see this tutorial I wrote in 2006 for the basic setup to make clothing GROW over a figure.

http://www.renderosity.com/mod/forumpro/showthread.php?message_id=2854479&ebot_calc_page#message_2854479

Export your clothing  from Poser as a single and welded object file.
Run that object through the cloth sim.
Then take it back to the setup room to rig it for your figure.

Happy Posering

Poser 1, 2, 3, 4, 5, 7, P8 and PPro2010, P9 and PP2012, P10 and PP2014 Game Dev
"Do not drive faster then your angel can fly"!