Er, not sure. I was up near the Fujairah-Oman border this weekend but didn't go through.
There's a recent update of some of the borders here:
http://www.uaeclimbing.com/forum/vie...e2c8c492018293 but it doesn't mention the one you need.
The LP suggests that the one you want is Khatmat Milahah (http://www.lonelyplanet.com/oman/tra...ing-there-away)

See this too: http://wikitravel.org/en/Oman