Ad-hoc wireless networks are for connecting multiple wireless devices together without a central infrastructure (like a router).
On wireless computer networks, ad-hoc mode is a method for wireless devices to directly communicate with each other. Operating in ad-hoc mode allows all wireless devices within range of each other to discover and communicate in peer-to-peer fashion without involving central access points (including those built in to broadband wireless routers).
A wireless ad hoc network is a decentralized type of wireless network. The network is ad hoc because it does not rely on a preexisting infrastructure, such as routers in wired networks or access points in managed (infrastructure) wireless networks.
So I would say there's no way to get any router to be set as "ad-hoc", so you're probably going to have to go back to whomever told you that and get some clarification from them. :)