A better way, in my opinion - would be buy a J ticket by paying £695 cash for WT+ to KRK-LON-SFO-LON-KRK, then mfu'g to J for 30,000 miles - then changing your baec number to an AA one. Don't quote me on that, as haven't tried it myself yet! (changing the number).

Drat - just realised about this no miles allowed on BA transatlantic thing, well subsititute SFO then for YVR or somewhere similar.