I assume the answer to be "no", but:

Is there any way to get an onscreen keyboard at the TDE login screen?

Actually this is the only "problem" left on this machine (Toshiba z20t): 
refind does not work, so it's impossible to choose the OS at boot and to 
login in tde without the keyboard.

This is not really a problem because I only want the tablet in special 
situations, but the problem just nags.

Have a nice day,

Thierry