Currently this isn't possible because of how the search works (it uses a single byte for the length). Can you use a shorter string, maybe with regular expressions to find the start and end of your special string?
Yes, I can use shorter search text at the moment and then verify if the full text is the one I want.
So it's not showstopper for me, just inconvenience: instead of pressing Ctrl+F, Ctrl+V, Enter I have to perform a series of manipulations.
Luckily I don't need to do this often.
Maybe TC could do something similar: search for the first 255 bytes, then compare with the rest?