Hi,
In that case, go to the TextMate preferences, create a new shell variable "TEX" and set its value to "latexmk.pl".
Go back to your latex file, do typeset and view, and everything is run automatically for you.
This is all thanks to the magic of the latexmk script[1].
Thanks for the hint. I knew about this script but I seem to have underestimated what it can do -- it seems to (generally) be able to work with bibtopic. However, I still seem to have some problems at the moment, so I will need some time to sort that out ...
Being able to created specialized scripts is valuable nevertheless, since I have a rather slow machine and won't want to go through the whole processing each time.
Thanks again, Matthias