I am the author of the course and will be tutor also.
I am meeting with the ICB guys next week and will raise this then.
In advance of that, and my interpretation - I would say that as soon as you have qualified at level II you could do this, simply because there is no set order for any of the Level III papers.
So you could do Payroll, or Self Assessment or Computerised in any order and I don't see any reason why this should be different, it is a level III paper which is not conditional upon you (or anyone else) having any or all of the other level III qualifications.
Of course the ideal scenario would be to get all and it looks like you are on your way already.
There is a Legal Bookkeeping thread on the forum so feel free to post there.
edited to correct spelling error.
Edited at 23 Aug 2011 09:10 AM GMT