Hi guys ,
be VERY carefull , from what I've read these sort of ports are usually for maintainance only, so may not be wired as per standard....i.e worst case you could have a fubar'd tv with no warranty, best case you wind up back with IR. I think you need to look for RS232C (control ?) in manufacturers spec,
Fyi I've just got a Sharp Aquos Lc46X20 and it's BRILLIANT , tho not quite plug and play as some would have you believe,
ALSO 1) be aware that not all models have the rs232c on them , check with supplier... i made it a condition of purchase.
2) make sure you have a cross wired serial cable (null modem cable) to hand, I'm using an old "laplink " cable which seems to work