As you say, the Windows MobiPocket Reader can get RSS feeds and make them into MOBI ebooks which can then be read on an iLiad. However, the MobiPocket software on the iLiad can only read ebooks, it does not have the management features of the Windows version (in particular, it can't get RSS feeds or MOBI ebooks over WiFi).
As tselling said,
Feedbooks.com iLiad Downloader (iNewsStand) is the only way I know of to get RSS feeds directly to the iLiad.
The iLiad makes very little use of the WiFi. For example, iRex does not provide a web browser. All the web browsers have been provided by the user community, and none are suitable for routine use (e.g. no bookmarks).