I don't remember where I got those codecs from. I downloaded them from somewhere in the internet. I'm even not sure which one does work. Maybe, it's Nimo (vers 5.0) collection of codecs (I'm not sure but I think it's mpeg4 codec what you need from this collection). For any case I installed all codecs from this colllection.
Or it may be 3ivx D4 PR2.
Sorry for so little help.