The proposed solution is in the tracker. If this is an autotools based package, and '--disable-silent-rules' doesn't work, you can try to add MAKEOPTS+=" V=1"
I was about to use waf-utils.eclass which has exactly the same "problem". Anyway, pushed as: > 09 Nov 2012; Sergei Trofimovich <slyfox@gentoo.org> xmms2-0.8-r1.ebuild: > Added verbose build (bug #442496 by Agostino Sarubbo). Thanks!