OK, I have managed to get all aspects of android-wireless-tether working in 2.1 with no hacks. I've even deprecated my Helper app It is no longer needed. Encryption still not working, as in 2.0.1, but Access Control now is.
This is a base 2.1 image based off Greek35T's 0.0.41. Only wireless tether has been installed, and it is ready to go! Simply login, start tether app, click start, and network should be visible. This also has the latest tether-2 script provided in this link, to which I owe great thanks for the great information:
With the new tether script the network stays visible also ...
Grab the base nandroid rom here:
4shared.com - online file sharing and storage - download 2.1-base-wireless-tether-BCDMRS-20100107-1655.zip
I also am working on a batch script to enable tethering in your existing roms, as I know a lot of you don't want to lose your apps/settings ... almost done with that as well and will upload soon. Will be very easy for noobs (no linux commands to enter, pretty much run a batch script in windows and answer a few questions).