Not in standard NWN. There a couple of hakpaks that bodge a mechanism for it though, a bit clumsy but you dont have to re-equip them all that often as their default equipment is quite good. And automaticaly improves as they level, which is just not fair. Most people have to hunt for a crossbow +3 with infinite ammo, but not the henchmen. They get it for free.
You can find the hakpak I use here:
http://nwvault.ign.com/Files/hakpack...21482987.shtml
It does a lot more than just inventory management, its makes the henchman AI a lot better, and you can order around them a bit better.