To chamber, you need a guitar made in two halves before the parts are stuck together (unless you want to saw it in half the difficult way). Or be prepared to remove a lot of wood, chamber it, then stick another bit back on.
Or you could simply cut round holes through it. I've seen a few Strat bodies modified that way. Russ Ballard (of Argent) had one.
Or simply rout/drill out wood that's covered by the pickguard.