Is there a mod that does this, and - crucially - one that would work with BGEE? It's really bugging me since I'm so used to her BG2 one and I'm having a hard time taking her as the same person (although I played BG1 first, about 12 years or go or so). Even that aside, she looks like some 38-year-old American woman who goes around selling Tupperware to her neighbours, not your plucky little sister.
There are very few mods for BG:EE, as WeiDu doesn't work with it (yet)
But you can do it.
I haven't got BG:EE, so I can't check the naming,
But if you make a directory called Portraits & put it in your Documents\Baldur's Gate - Enhanced Edition directory
ie Documents\Baldur's Gate - Enhanced Edition\Portraits
Then put the attached resized imoen portraits in it, it should work.
If not, rename them IMOENM & IMOENS
You could also try putting them in your Data\Overide folder.
Edit: Sorry, you will have to save them as .bmp's, I can only attached them as .jpg's
Open the jpg's in Microsoft Paint & then click save as 24bit bmp.