I run it on Ubuntu with Installer 1.0 that just came out. The software comes in .deb package so I am sure you can try to install it on Debian and see if it works. Be default it's installed in /usr/local directory.
Here is the download linkhttp://patch.codelathe.com/tonidosheeva/TonidoSetup_arm.deb
The version for the sheevaplug is licensed, it costs 29 dollar. I don't think they will be happy if you provide a download link. Besides that i don't think it will work because when you setup an account they check your plug's mac address. If it is not registered it might not work.