I think, tedious as it may be, that you need to read Part 61 carefully.
I think too that EASA rules recently extended the expiration deadline from five years (60 months) from expiration of rating to seven years (84 months). Certainly that works in terms of renewing what was a JAR/OPS IR. It may be that there is a subsequent Notam in SA extending the period down there.
http://www.caa.co.za/New%20Notices/C...TIONS-2011.pdf
Air Law is now a little amplified in coverage and has become Air Law and Flight Procedures.There are several flight school that produce notes for self study.
It's trickier than the old Air Law though.
Otherwise, if you've held a valid commercial licence outside SA you can write to the director submitting certified copies of logbooks, licences, checks and a motivating letter explaining why you should be exempted form a rewrite of the usual com subjects. This might be successful but is likely to take time.
Not sure if the information above is 100% accurate or up to date but hope it helps or attracts comments from those more on the ground than I.