I guess I wasn't clear. I'm not looking for a manual method (like handtyping 'source...' after I login) but an automatic one like I can do on other Linux distros. I thought the second link in my original post (
aliases under BusyBox) would help explain what I was going for.
I'm experimenting with Scratchbox cross compiling and I'm using the command line a lot on the Kindle, and launching multiple Kindle shell sessions.
Thanks for the replies, though. I'll just change /etc/profile to source something in /mnt/us.