I think it would make more sense to trigger this script when loading this project. I typically (based on my project) require 3 things to change
1. The actual WSDL (integration, dev, QA environments)
2. username / password for methods (since our services are secured)
3. any groovy scripts which might access the database (insert, update, etc)
I was able to solve the third problem very gracefully by writing a outside library using groovy repository feature in soapUI 1.7.5.
Basically any solution that would allows switching of WSDLs with relative easy would be very helpful. Currently I just use notepad ++ to copy/replace wsdl. However, my ideal scenario would be run a series of test in multiple environments without any manual intervention.