It sounds like more what your talking about is eZ publish itunes extension to extend generic rss 2.0 to include the (non-standard) itunes tag markup...
//kracker TV : Curb your Enthusiasm : The Mantra : Ja Ya
we have extended the original RSS-Export-Module to integrate an enclosure-Attribute in the feed, the main difference between Podcasts and RSS 2.0. I'll have a look at it and will post it to contributions as soon as possible.
Once installed, you can define your feed as before, but there'll be an additional Fieldset where you can choose an enclosure attribute from your custom class. It btw supports Siteaccess-specific Feeds that are only working in the specified siteaccess (great for multi-sites) and multiple Attributes in the description field.
<b>Have a look at</b>: http://ez.no/community/contribs/import_export/syndicate_rss
I, for one, am interested in your (unique/modified) "ezrssexport class" which includes the "podcast extensions" that works so well for you.
I'm certain many others (unspoken) also are interested in seeing this unique set of changes contributed (posted) here on ez.no (<i>http://ez.no/community/contribs</i>)
Please do post your code here on ez.no as a contrib.