[LVL ED] Segmenting Items Within the Editor

[Paddy™]

I'm new to the HPL tools, and the wiki doesn't seem to answer this particular question, so here goes:

Is it possible to cut, split or punch holes through planes or other structures directly from within the level editor? For instance, let's say I have a floor made from a plane and I have a well extending down through it. The hole in the well will be filled with the floor plane, because it passes right through the hollow tube of the well - can this hole be "punched out" of the plane?

This is an example of what I mean:

Pic 01
Pic 02

Thank you for not making fun of my complete newbishness.