I've been using sandboxie and text mode idling for the past year. With Windows Vista & 7 you don't need to worry about moving the steamapps folder or tf2 folder/files. Just copy everything in your steam folder except the steamapps folder to a directory on the root of your C:\ drive.
I have mine set up like this.
C:\idle\steam1
C:\idle\steam2
etc..
Then I just make a symlink to my steamapps folder (Credit to Facepunch for this):
Code:
cd C:\Idle\steam1
mklink /D steamapps "C:\Program Files (x86)\Valve\Steam\steamapps"
I don't use a .bat file to launch the accounts though, never had success with that, so I launch each steam and tf2 hl2.exe process manually.