Several different docbook to manpage tools are available, including docbook-to-man. The other twos I know of are db2man and docbook2man.
OpenSolaris doesn't provide docbook-to-man by default. The docbook2man can be built from source. The attached patch can fix the build error and could support the above-mentioned three XML to manpage tools.
Update the patch to apply to Makefile.am instead.
File Added: lxsession-01-docbook2manv2.diff
patch v2-1
oops, this one is correct.
File Added: lxsession-01-docbook2manv2.diff
Patch included in rev1307.
Thank you very much.