[WORD 2003] Is there a way to run a macro (or run any code) on pressing the return key, provided the current paragraph has a particular style applied?

I have set up a macro to insert a numbered list item using a {SEQ} field (I have my reasons for wanting to use this instead of the built in list feature), is there anyway to run this macro on pressing the return key if the style is already set to 'Roman List' which is the style I created for these lists? Or alternatively copy and paste the macro code to wherever this key press conditional code is?

I've done a lot of searching and not had much luck so I'm not hopeful, but any help would be appreciated.

Thanks!