Deployed Combine Gun

[Cunbelin]

I'm having a little trouble finding the deployed gun model, and I'm not sure what entity would be best to use for it, anybody done this yet ? I was trying to use prop_vehicle_cannon, but the lack of a model makes it hard to work. Oh and since I'm asking the first question, is there something special I have to do to get an enemy to man the gun or will the AI do this on it's own ? Thanks for any help!