You can then taint one of your coins with coins which only exist on one of the forks. Let's say you get a few satoshis from block reward which occurred in a XT 8mb block (thus is not valid and does not exist on the 1mb chain).
Of course I know that.
Yes, of course. LOL!
But how do you get those few satoshis?
Try just South of where you found the 'taint'.