I haven't looked lately, but I suspect:
DO_NOT_COMPILE="component1 component2" \ ./configure --prefix=$TRINITY_PREFIX ...
may work. At least that worked in koffice-1.6.1.
I have not posted any follow-ups, but yes, a few days ago I discovered that option. Another option seems to be to edit the subdirs text file in the sources root directory.
Although these options work, and I have tested them to some degree, there seem to be some internal dependencies that I have not yet isolated. For example, I seem unable to build kword unless I build kspread too. I'll keep playing with those options. Perhaps eventually I can post the information to the wiki.
I believe the Arch people at one time built all kde3 packages this way. I have been unable to find that information or specific build scripts to study. I think a few tweaks here and there are needed to take full advantage of these build options. Knowing what they might be would be nice.
Darrell