yep, edward has a good point
if the trans is heating up just as fast as the engine the heat transfer could be an issue if the tranny is the problem.
being they are connected together the heat could transfer through the tranny into the engine.....
though sometimes its hard to distinguish which one is the problem though. maybe you could get some heat indicator strips and stick one on each component to see which one starts showing indications of overheating while checking pressures

checking the tranny is a good idea so you can either find the problem or rule it out all together :o)