[boost] [Build] How to build libboost_lzma?

Up till now I have built libboost_zlib and libboost_bzip2 by setting ZLIB_SOURCE and BZIP2_SOURCE variables to their respective source directories on the bjam command-line and the libraries get built without fail. I gather (from the bjam output) their is now support for lzma, which I would like to use. I've tried a similar (did not find a doc) approach with LZMA by feeding "-sLZMA_SOURCE=c:\xz-5.2.3" (from https://tukaani.org/xz/xz-5.2.3.tar.gz) to bjam. This does not work. How do I make bjam build libboost_lzma? Thanks in advance. degski -- "*Ihre sogenannte Religion wirkt bloß wie ein Opiat reizend, betäubend, Schmerzen aus Schwäche stillend.*" - Novalis 1798