This patch to the ebuild fixed the problem

librecad-9999-20120606.patch (text/plain), 499 bytes, created by Guenther Brunthaler on 2012-06-06 21:16:54 UTC

--- /var/lib/layman/science/media-gfx/librecad/librecad-9999.ebuild	2012-05-26 08:13:06.000000000 +0000
+++ /usr/local/portage/overlay/media-gfx/librecad/librecad-9999.ebuild	2012-06-06 21:01:44.000000000 +0000
@@ -34,8 +34,8 @@
 	insinto /usr/share/"${PN}"
 	doins -r unix/resources/*
 	if use doc ; then
-	dohtml -r support/doc/*
+	dohtml -r librecad/support/doc/*
 	fi
-	doicon res/main/"${PN}".png
+	doicon librecad/res/main/"${PN}".png
 	make_desktop_entry "${PN}" LibreCAD "${PN}" Graphics
 }