Another way is to use modules (ttn-do zzz xhtml-tree)[0] and (ttn-do zzz publishing)[1]. All of gnuvola's html, modulo texinfo output, is rendered that way. Likewise, the servers grumi[2] and sizzweb[3] compose using those modules.
Same idea as the others proposed, different dependencies. thi [0] http://www.gnuvola.org/software/ttn-do/ttn-do.html.gz#zzz-xhtml_002dtree [1] http://www.gnuvola.org/software/ttn-do/ttn-do.html.gz#zzz-publishing [2] http://www.gnuvola.org/software/ttn-do/scm-html/grumi.scm.html.gz [3] http://www.gnuvola.org/software/ttn-do/scm-html/sizzweb.scm.html.gz
