I'm considering making a 40X into a switch barrel and had a few questions. It's my understanding that most benchrest rifles are set up to be switch barrel rigs with no special tools. Does that mean that the barrels are only twisted on to "hand tight" specs, or is there more too it? If they are only hand tight, does it take a different barrel threading or action thread that allows for this?

While I have seen a BR shooter put a barrel on by hand tightening it, and then shoot the whole match, it it not something I'd advise.
Addressing your question about your 40X, many of these fine actions have been set up as switch barrel rigs. Most of the time the recoil lug is pinned to the action and, sometimes folks have them TIG welded. No special thread is required.