I left off with instructions for creating an eabi / maverick toolchain for the ts72xx boards from EmbeddedARM.com, and am still sifting my way through some pretty dense decisions.
First of all, Gentoo's Portage build system makes it really easy to cross-compile packages and maintain dependencies. I think it's fantastic. The ony tricky part is in how the package database is maintained on-board. It's not even a database actually, it's right in the filesystem. Depending on the block size, even a 2-byte file could take up 4 kB of space, which is way beyond anything conceptual for an on-board package database for embedded devices.
I've considered writing in some sqlite code into the 'qmerge' app that comes with portage-utils. The benefit is that the sqlite file would save potentially doezens of kB of space. Furthermore, the sqlite file could be compressed in the filesystem after updates have taken place. When any package maintenance needs to be done, the sqlite database could be extracted to a tmpfs-mounted directory, and all of the operations could be performed there.
An alternative to that, is actually just to use the current filesystem-based package db and simply compress that directory without the sqlite backend. Then when updates were necessary, it would be possible to extract that to tmpfs, and re-compress when done.
Time is of the essence on my latest project, so it's likely that I won't be able to fully code that into portage-utils until my current project is matured and nearing completion. The matured stage is probably 1 month from now, and the completion stage is probably closer to 2 months away.
I'll post my instructions, as planned on gentoo-wiki.com for doing cross-compilation and building up to a certain stage, but more instructions on how to maintain packages on a live system may be delayed for some time.