Well, for one, I don't have a hacksaw.
2nd, how does one dismantle the quill in order to saw it? (probably a super noob question but i've obviously never done or considered it before)
When you say the angle, you mean cutting it so the tightening wedge at the bottom fits snuggly against the newly sawed bottom of the quill?

wouldn't it just be easier to buy a shorter stem?