From what I have been able to figure out from different web sites is that you pretty much have to be a national to be able to operate in UAE. As far as Oman, they do not issue licences for short term visits (if you were going to be there for a year or two, you might be able to get one), but you can request to be a guest op at A47RS. There address is:
Royal Omani Amateur Radio Society
Postal Code 113
You could also try to contact the UAE's IARU society (their equivelent of ARRL) and double check to see if there is anyway you can get a license.
Best of luck and 73
(also, if you are ever wanting to visit anywhere else, check out http://www.qsl.net/oh2mcn/license.htm