split modifier for template tags?

Greetings,

We all love 'split', so is there a way to split a template tag?

I've got a custom field called "relatedstories" defined via Preferences that takes a list of entries as input. Currently, it's just a text field and users have to do the HTML with <P>: and <:BR> tags to output them in list form, and I don't get to do anything with them. What I'd much rather do would be for users to enter a CSV or \n-delimited list and process it myself, like so

<mt:relatedstories split=",">
/* do some stuff with a related story*/
</mt:relatedstories>

Unfortunately, I don't see split or anything similar as a tag modifier anywhere in the list, and I'd really like to not have to write a module if there's a way around it. I could also add unique custom fields for each story, since there is a limit of 3, but that's kinda ugly, too. Is anybody else doing something like this, and how are you handling it?

thanks,
Bill