Tuning a 98 jaguar xk8

I built my 3kgt vr4, and my father is interested in modifying his 98 xk8, he wants to keep it automatic and the transmission is controlled by the ecu, which makes a standalone very difficult if not impossible, i have heard of people flash tuning these ecus, does anyone know if there is hardware and software capable of flashing this ecu?

It may have the ZF transmission - ZF5HP24 - and there should be ECUs with control options for that.