Jai,
For any ICAO CPL/ATPL to GCAA CPL/ATPL
If you are a non-GCAA national, you will need to have a flying or flying related job in the UAE first and then thru that company you will write the the Air Law exam at GCAA.
For PPL
You can however, convert your PPL+IR without having a flying job in the UAE as long as you have a UAE residence visa. Rest procedures as suggested by OMDBpilot....
Cheers