I know quite a few people do it, but my thinking was that boosting the full range ouldn't give you an alternative to a channel switch, which is what it sounds like OP is after. It would give you a big low end boost, on top of distortion, as opposed to just dirtying up the signal while maintaining a constant level.
Having said all that, I've just checked out the Streamliner 900 and it looks like the control you're talking about is just a gain control, so I'm wrong, you do just want a boost. Alternatively it's just a push switch so it'd be fairly easy to wire that up to a jack on the back you're not using, and plug a footswitch in to that.