Custom attachment name when pressing email button

Hello everyone,

Who knows a possible solution for the following:

When I click my e mail button on the custom interactive form (e.g. custom salesorder print, or custom contract print etc.) it creates an e mail with an attachment name such as: 133a078_21461.pdf (by using the event.target.mailDoc function).

What I want is to build up my own attachment filename such as SalesOrder2010-12-30.pdf

How can this be best achieved?

I already searched the 'whole' internet, but couldn't find it. What I don't want is to create my own javascript file and save it the pc of each enduser. I already thought of the possibility to do some coding on the ABAP side, just before the form is started... but I have no clue.