Well, Dan Ingalls did something a like that. He implemented a Squeak VM in Java. It's six years old, and even then it didn't run a current Squeak image, but it works pretty well.

Announcement here:

http://lists.squeakfoundation.org/pipermail/squeak-dev/2006-...

JAR file here:

http://weather-dimensions.com/Dan/SqueakOnJava.jar