An experimental update stream to track trunk development for Squeak 4.6
is at http://www.squeaksource.com/TrunkUpdateStreamV3

Project description:

As of the release of Squeak 5.0, trunk development proceeds in the Spur
image format. Squeak 4.6, which was released immediately prior to 5.0,
is the last released image in the V3 image format. Because of basic
changes in the image format and associated VMs, it is not possible to
update a Squeak 4.6 image directly from the trunk update stream.

This project provides an update stream with V3 versions of the four
packages that diverge for Spur. The V3 versions of the Collections,
Kernel, System, and Compiler packages are maintained here.

Update maps are named update.V3. To adopt this update stream beginning
with a fully updated Squeak 4.6 image, use the preferences browser to
set the update URL to http://www.squeaksource.com/TrunkUpdateStreamV3
and set the update map name to update.V3

This is an experimental project, and probably will not be maintained
on an extended basis.

Dave