You can use signEZ within Lotus Script if you wish by doing a command line call to signEZ. In the signEZ database, you can access the PublicScript script library which contains the default implementation for all the calls required by the database. This library can be modified to fit your specific needs as long as you keep the structure of the BATCH documents, JOBBER documents and Command Line.
The most basic code to call signEZ is :
Reply% = Shell({signEZ.exe "=C:\Program Files\lotus\notes\notes.ini" "" "Ytria\signEZ.nsf" -be "6241"})
In PublicScript, there is a sub called ShellExt that creates the whole command line for you and does the shell execute.