Create an NPC of any Merchant class.
*Do not check autocalc stats.*
Press the AI button and you'll see where you can choose his services.
Create an Offer Services AI pack or add a default one.
More detailed tutorials about merchants can be found at http://tesalliance.org/forums/index.php?/topic/2578-npcs-ai-class-3/ or at the http://cs.elderscrolls.com/index.php/My_First_Shop.
Oh.. no "Autocalc stats"?
Damn i was thinking that i could a package for my companions, a time of day to recharge / repair items.
So I suppose that it cannot be done.
I can have both (have them level with me and fight with me, and recharge/repair items when they are not following...)