There's welding, and there's welding... If the vertices that need welding are already exactly coincident (don't worry if that means nothing - they usually will be in conforming clothing) then UVMapper will do the job - but by far the easiest method is to select the "weld identical vertices" option when you import the clothing into Poser.

I agree with what the others have said about modelling, but when you're working on a scene, the last thing you want to do is take time out to learn something new. It's worthwhile setting some time aside to do that later, though. :)