I find ghostxps (from http://www.ghostscript.com/download/gxpsdnld.html ) quite useful for converting xps files to pdf, and it can do a lot more, but there seems to be no ebuild for it.
If I'm reading the website (http://ghostscript.com/GhostPCL.html) correctly, there's already a bug about it. *** This bug has been marked as a duplicate of bug 121709 ***