How to apply output rules to script tag's content in IIS7 rewrite module v2?

Question

Hi,

I want to specify that my output rule should only apply to the contents of a tag... the predefined tags allow me to change the url of the src attribute of the script tag, but I want to change any URLs specified within any snippets of javascript embedded in my page.

I've looked at using custom tags for this, but it still seems to be attribute based.

I don't really want to remove the tag filtering entirely as I think this will have a negative impact on my site's performance.

Anyone with any ideas? Thanks, Mark