I did some more research and it looks the problem is thornier then I thought.

A code similar to this (which is also discussed in Dynamically altering static TT templates - by Ovid) would appear to cut it, but I am loathe to use such hackery - chiefly inside an Apache::registry script.

component.name does not cut it, by the way.In the end, every path that I'v been able to squeeze out of the template, filters and plugins refers to the script dir (not the template), or it's relative to the template dir

And yet the task I need to do looks mundane enough that somebody would have needed it... (the task, put briefly, is - get a list of template filenames, find the best match with a given dynamic rule, include the selected template)

I will heed merlyn's advice and go to the TT2 list, but it looks pretty hopeless so far.