Well how? Please tell me this is possible. Everything about GRAW2 so far kicks major ***, so surely this is possible

By change I mean cycling through primary/secondary etc.

You can not. The only thing you can do is, giving the order "go recon" to individual team members or giving the order "ALL go recon". This results in them changing from primary- to secondary weapon. It can be useful when their secondary weapons are equipped with silencers..
The order "(all)go assault" makes them change back to their primary weapons.