Somewhere there is a thread on this, and I tried a suggestion that worked.
Make a small spacer bead, then add glass to one place on the bead and smoosh it into the shape you want. I had to add glass more than once until I got it the size/shape I wanted.
Don't forget to keep the spacer warm.
Ah, found it. Look through this thread there are a few different ways mentioned:
http://lampworketc.com/forums/showth...58#post3953158