just put in the components of velocity that give you the angle of attack you want..
It's best to keep the flow as normal to the computational cells as possible for best cell efficiency. I'd put the part into an assembly and put an angle mate between the assembly pane and the part plane to control AoA. You keep the flow in line with the global CS and hence the computational domain that way. I think in my example from this post ( Wing lift off by a lot ) on the NACA 4412 has the AoA setup.