Someone on the WebObjects-Dev list, known only as "LD" just posted a tip about getting CodeSense completion working in XCode2 for WebObjects code. I took his tip and wrote an easy-peasy shell script that got the job done on my 2 machines.
If you need to enable CodeSense completion for WO, just grab a copy of this script, and run it in Terminal.
$ ./xcode_webobjects_codesense
You may first need to chmod +x xcode_webobjects_codesense first, to get it executable, but that's about all.
Thanks to LD for the detailed description!