Are you asking where it is if you are already tuned into ITV? Or are you asking how to tune in to ITV in addition to STV?
If you are already tuned into ITV then it will be on or above channel number 800.
If you are asking how to retune to also have ITV then you should be aware that this may disrupt subsequent recordings. See section 2 http://hummy.tv/forum/threads/things-every-hd-fox-t2-hdr-fox-t2-owner-should-know.1858/#post-28589 for a description of what you may experience if you go down this route without subsequently retuning so that you return to having just STV. If you don’t mind the hassle then to help you retune what is the HDR-FOX-T2's software version (MENU -> Settings -> System -> System information - 2nd white line down).