I assume you are talking about what is called an 'aggregated page' where a number of podcasts from the same provider appear on the one iTunes Store page.
In order to do this they need to firstly have all the relevant podcasts submitted, approved and accessible in the iTunes Store. Then Apple's instructions say:
If you have multiple podcasts listed in the iTunes Store, Apple can create a single page, called a “provider page,” to list all of your podcasts in one place.
To request a provider page, contact us. Include the following:
- - Podcast provider name (without extra information such as “Inc.,” “LLC,” and so on)
- - iTunes Store links to your podcasts (to obtain the URL, control-click the podcast title in the iTunes Store)
( http://www.apple.com/itunes/podcasts/creatorfaq.html )