The file you want is C:\Windows\System32\OSK.Exe
Run Group Policy (Start > Run > GPEdit.MSC).
Go to Computer Configuration; Windows Settings; Scripts (Startup/Shutdown)
double-click on Startup.
Click on the button Show Files... and in the newly opened window
right click and create a new text file.
Rename to osk.bat
Right click & edit the file
put in it the following line:
C:\Windows\System32\OSK.Exe (check this is the correct path for the machine you’re using!!)
Save & close the file
close it’s folder window
in the Start Properties dialog click Add...
type OSK.bat in the script window
Select OK twice
Still in Group Policy, go to:
Computer Configuration; Administrative Templates; System; Scripts
on the right pane, select Run startup scripts synchronously
double click on this option
change to Enabled (This will make sure the logon process will continue even though the script
has not ended).
Shut group policy
Restart system - the on-screen keyboard will be available about 5-10 secs after the logon screen occurs.
Put any other access tools into the startup folder as normal