I have ThingLab mostly working under MVC in a squeak 3.8 image.
I ported the base source code to Monticello, and posted it to
squeaksource:
http://www.squeaksource.com/ThingLab.html

Installation instructions and known bugs are on the Swiki:
http://wiki.squeak.org/squeak/607

I have not tried it on a 3.9 image yet, feel free to try it and
let me know what happens. 

-- 
Matthew Fulmer -- http://mtfulmer.wordpress.com/
Help improve Squeak Documentation: http://wiki.squeak.org/squeak/808