I doubt you'll get hangarage for a B738. Julius Berger have a hangar for their turboprops and Chanchangi have some sort of maintenance at the domestic ramp but i doubt you'll be able to get any space for a 737 or that they'll let you use them. The presidency has a hangar that houses their BBJ and other bizjets in their fleet but i bet they won't let you use it. You'll probably be parked at the international ramp for the duration of your stay.
Contact landover aviation, they seem to handle most of the foreign bizjet traffic in Nigeria. Hope I've been of help.
Capt Manuvar