(10/17/2010) It's embarrassing, but I'm only now to this point. I spent some time getting Ubuntu installed on an old machine, but an update seems to have clobbered the boot sector or something - and frankly, that machine has been a problem for a while now. So this week I built a 32-bit Ubuntu virtual machine on my desktop box, and I'm chugging along.
After making my earlier changes again (the ones I made on Fedora), things are compiling well. I'm getting a lot of warnings from including logos_libs/ruleengine/rulebase.h of the form: "%.2d" expects type 'int' but argument 3 has type 'long unsigned int', but aside from those warnings, things worked fine. I'm going to have to look into those.
Ah. In lgsentity.cpp, "warning: deprecated conversion from string constant to 'char*'", and in a couple of other files, as well.
I ended up adding various headers to about ten files all in all. Not too bad.
The installation routine failed to create /usr/local/share/openlogos/bin for some reason - acting as though it wasn't running as sudo root. Strange, and something that should be examined.
But ... I seem to have installed OpenLogos at long last.