Viper, the A/C aren't skinned with a BMP in the same way the A/C in AW were..they're a true 3D rendering, and as such arn't amenable to user manipulation.
To paint your plane, you'd need to code hack the game, with all that that implies.
The only BMP's in the game are the custom nose art patch (Squads only) and the gun sight.
On the other hand.....there's always the terrain editor if you feel a need to get expressive, although it's not the same, I know.