I wouldn't say there's a canonical way, but I guess you'd want to create a new biff app and then either move the parts of biff you want into your existing app, or move the code from your existing app into the new biff app--whichever seems easiest.

(my guess is that moving your app's code into a new biff app would be easiest)

Thanks, I figured as much but I was hoping I was just ignorant of some way to just pull in parts of Biff as libraries

What parts would you want to pull in? right now everything's in one monolithic library (com.biffweb/biff), but I'd be fine to do a little restructuring to make it possible to pull in individual parts. I've just been waiting for a concrete use case to come up.