I'm wondering the same thing.
I've tried to create a bashrc
(/.bashrc ; /system/etc/bash.bashrc ; /root/.bashrc ) But none is working.
I'm about to try a different way,
I've cp /system/bin/sh to /system/bin/sh1
then I'll try to replace /system/bin/sh by a shell script that will launch my aliases then sh1
alias lsa='ls -Alh '
But i'm not pretty sure It could work properly. Firstly because I remember a gain-super-user manipulation that requires to copy and modify rights on sh. (but it could be ok if the script and the copy of sh have the same rights).
Secondly, because I'm not really OK with this; When I'll remove /system/bin/sh in order to replace it, I'll have no shell for a time (if it crashes, I'll not be able to use sh anymore, even with adb).
So if anybody have an other solution it could be damn cool
Thank you all
EDIT: I've just tried this. It's ok, I've not lost my shell, but the modifications (one alias, and a path export), are not applied.