Hi Rolf - that depends on how the script is written - if the script does not ‘call itself’ then you can add it in Options > RhinoScript and create your alias, and it should work. If the script does call itself, then you should modify it so that it does not before adding to the list of scripts to load at startup.
Option Explicit
Call Main() '<<<<< this calls the Main subroutine - it needs to be removed.'
Sub Main()
blah blah blah
End Sub
-Pascal