I haven't ever developed Tri-X but have developed TMax 400 and I needed about 4 sequences of pre-wash with occasional agitation and dump to rid the film of almost all the dye but looking at the posts for some commonality I'd hazard a guess that D Allen's process of double fix and overall a similar amount of washing as my pre-soak and dumps would be even better.

Incidentally while I do not wish to dissuade you from continuing with trad B&W film, I'd suggest that if you are stuck with scanning for the foreseeable future you might want to consider XP2+. It is said to be easier to scan and yet retains excellent darkroom printing qualities.

Of course it requires the C41 process which has the added potential difficulty of retaining a higher temperature of 37.8 if you want to develop it yourself but does have the advantage of being able to be processed in any mini-lab, not many of which are geared up to trad B&W film development.