[boost] [build] How to build a multi version non-header-library

Hi, I want to provide two versions for Boost.Thread, one using Boost.Chrono and the other not. Boost.Thread is a non-header-only library so I guess that I need to build two libraries with different names. Is there already a library in Boost in the same context on which I can base my build design? What is the simples way to do this with Boost.build? Any pointers to the doc? Thanks in advance, Vicente