This package is not currently loadable. The package owner has been contacted to assist in correcting this. (klc, 7/4/2008)
CompressedSourceStream writes files as a series of GZipped segments that can be written and read sequentially like regular source files, and yet remain compressed 4x on the disk. Full sources for Squeak 3.6 fit in 3.5MB.
Smalltalk compressSources will write a copy of the sources file in this format. Thereafter openSources:forImage: will look first for such a compressed copy, and open it if found.
Should work for .changes files too, but I haven't bothered to test.