Seeking global txn test info

I am seeking a test outline (or guidance at least) for testing iAS 6.5 global transactions with oracle 8.

How far down the rat hole did you go in simulating errors that could cause a rollback? There’s the iplanet errors plus the oracle errors, and all the combinations of such it makes my head hurt. Is it sufficient to throw an error, or do you really have to test out all of them at all of the potential failure points?

The info I have found for my test plan has been haphazard and mostly inferred from iplanet admin config instructions and oracle readme files on distributed transactions.

Any experience or advice from someone who has tested global txns before would be MOST appreciated!!!