The wolips.properties file tells WOLips (and the Ant based build) where to find the various parts of WebObjects and friends. This replaces the wobuild.properties files used by earlier version (pre-New Hotness) of WOLips.
The location of this file differs by operating system:
C:\Documents and Settings\<user>\Library\Application Support\WOLips\wolips.properties
The wolips.properties file should be created automatically, but if this does not happen, it can be created manually (e.g. with a text editor). Example contents of this file (modify to match the locations on your machine):
wo.system.root=/System wo.user.frameworks=/Users/chuck/Library/Frameworks wo.system.frameworks=/System/Library/Frameworks wo.bootstrapjar=/System/Library/WebObjects/JavaApplications/wotaskd.woa/WOBootstrap.jar wo.network.frameworks=/Network/Library/Frameworks wo.api.root=/Developer/ADC%20Reference%20Library/documentation/WebObjects/Reference/API/ wo.network.root=/Network wo.extensions=/Library/WebObjects/Extensions wo.user.root=/Users/chuck wo.local.frameworks=/Library/Frameworks wo.apps.root=/Library/WebObjects/Applications wo.local.root=/
See Using WOLips With Multiple Versions of WebObjects for how to use different wolips.properties files with different WO version.