In order to access a BES your device has to be provisioned by your wireless provider. You won't find any documentation because this isn't something you can take any part in (other than finding the support agent at your provider that knows what is going on.
I suspect that since the BES data switching is actually done at RIM it has nothing to do with the sim (but this is a WAG).
BES provisioning is relatively new. I was tinkering with BES Express a year ago and my blackberry worked fine. When I recently installed a full BES and tried to activate my Bold I had the same problem as you. Some rogers agents told us we needed to buy $K15 worth of software (the BES) which we already had. Took nearly a week to find the right person.
One trick that might work is to have the RIM support person that gives you that answer forward your call to someone at your carrier that they are sure knows what to do.
My other Blackberry is a PlayBook.