acutally its very possible!
I use PI 7 I'm not sure what edit number you are using.
if you use your cutting tool it can cut to any shape you like just look on the tool bar after you choose the cutter.
on the bar will be mod, then shape. I usually keep mine in rectangle

if you are wanting to MAKE a shape with PI
choose the shapes button then click in your working area
if you click on shape then it will take you to an area where you can choose what shape you would like to use.
if you don't want to use any of the reg shapes you can
pick from the shape gallery where there are LOTS of goodies by picking the little man icon. or ( CUSTOM SHAPE)
also if you want to erase any of the area that you have made with this shape making tool you need to go to object, then convert object type from text/path
then viola you can erase part of your object. This is an easy way to use to make tags too! make the shape then erase out the circle for the tag opening.

hope this makes sense if not then just pm me ok! i'll try to make things more clear!
Dawn