You could try using moe's vpackager to configure/make/install your koffice package. What it sounds like you have is the source code for koffice in which case you'll need to unpack, configure, make, make install/checkinstall the package to get it installed. M0e's created a nice packaging utility called 'vpackager' that can help to automate this process for you.
-Perhaps koffice is already packaged in the VL repository somewhere, which would be the easiest solutuion.
-You could try using a koffice package from linuxpackages (slackware packages) for v12.
I don't really know, but it's possible you'll run into kde dependency issues trying to use koffice on VL-light???