Oh ! that's fun, I just found your post on the more requested feature request from the french mirror of mediaportal (mp-fr.com).
I just fetched all the cvs today for starting a development of an iptv for implementing VLC as an internal player of mediaportal to be able to watch french adsl tv (freebox from free.fr), & I just started to look how was written the TV plugin for getting it & just changing actions & all other calls to tvcapture for calling vlc instead.
This idea was to keep exactly the same look as the normal tv plugin because we can find nearly the same features in vlc & specialy with the freebox (epg, timeshifting, ...).
Really enjoyed to see that some other guys are interrested.
I investigate to know how to make vlc more generic, & one of my idea was first to write a WDM video tuner driver layer for accessing vlc features & make it generic for iptv. But as it runs at a lower ring, & because, the ddk cannot simply be found on internet & needs to be register on the Microsoft, I decided not to continue on this way... but I think this was a great idea. Not by implementing the activex but more the vlc kernel directly in this bda driver...
Imagine, just having iptv generic & accessible from all softs, not obliging media portal team to write a new plugin, just "add" a new card !!!!
But that's true, writing a media portal plugin will be more simple & that's was my second idea... I just fetched all media portal source code, compiled it, started to play with the activex, but nothing else....
So there are two ideas :
-Writing an IPTV low layer (DBA driver)
-Writing a media portal plugin..
As I don't have lot of time to spend on a dba driver because it is a little bit more sotisfacted than a mp plugin,
If some of you are interrested for writing a bda driver why not, which could be installed through the vlc installer

, I am also interrested.
Anyway... is there already anyone who start writing a TVIP Plugin getting all the look of the TV normal plugin ?
Is there who already started something on this subject ?
Thx, in advance,
Louis