Hi there,
You'll need:
ATPL Exams all passed (14 of them)
15 hours of instrument training to convert your IR.
As many hours as you feel you need to prepare for the CPL skill test. There is no specified amount.
To convert your ME rating you'll need to do a skill test but this can be done at the same time as your 170A ( A flight test to see if your ready for your skills test.)
You will also probably need to get a JAR radio licence as I don't think the CAA recognize the SA radio licence as a straight swap.
Thats what you gotta do.