Link keyboard shortcut to macro

[hardieca]

Hi,

I've create a macro that encodes all special characters as HTML
entities, and I want it to run every time the user saves the document.
I can link to the macro on the toolbar and the File -> Save command
under the File menu, but I want the macro to fire when the user hits
Ctrl-S as well to ensure the macro runs.

Currently Ctrl-S saves the document, is there any way to overwrite
that?

Many thanks,

C.