[gentoo-portage-dev] can an overlay force a USE flag on a host?

[Amit Dor-Shifer]

In cont. to my prev. question 
(http://archives.gentoo.org/gentoo-portage-dev/msg_9973fd6c12d7c2088457697f49ea2f5e.xml)

Can I append use.force/package.use.force/package.use or similar to an 
overlay, and by that control USE flags on the host?

Though not necessarily related, I'm trying to resolve a broader issue: 
whether it is possible to extend a profile via an overlay.

I've read http://bugs.gentoo.org/show_bug.cgi?id=133740#c6. Also, I've 
found http://en.gentoo-wiki.com/wiki/Custom_Profiles which states how 
custom profiles can be integrated into a system, yet with the caveat of 
modifying local portage files (removing the symlink to the profile). I'd 
appreciate to know if it's also possible to gain similar results w/o 
touching files on the hosting portage setup.

In a/m bug, the lack of documentation in this area is mentioned . I'm 
wondering if this has changed since those comments were written, as I'm 
confounded by bits and pieces I'm fishing out w/google.

Amit