Making an actually useful Bo is very difficult with some materials, a practice Bo for building strength and what not can be a Rattan Staff, I've used them in the past....
The problem with using hardwoods, is the fact that you have to either grind down, chisel down or carve down a single staff. (I've heard different height lengths from different practitioners, I prefer a staff that is about eye level for Actual competition, but for actual weapons sparring/drills I prefer one that is slightly over my head for a bit of extra length (for finger protection) so... tailor it to how you want.)
If you want to find out how to treat the wood, get a book on wood conditioning. You'll need some money though, its not a cheap endevor to make a strong hardwood bo. Some require heating, all require oil of some sort. Its a pain in the butt. I've tried it.. But... Unfortunately I failed
I made a Bo, but you can ask Bushi_No_Ki about what happened to it...
(It ended up snapping at a tournament that we both happened to be at. I over conditioned it a little... Heh.)