you can use vec_accelerate and accelerate as often in as many function as you like.

I am sorry, but "vec_add(camera.pan,accelerate(aspeed,0,0));" is nonsense. vec_add expects two vectors. Accelerate returns the distance to cover in quants, i.e. a scalar. I guess the other two missing vector elements will be random memory from the stack in your case. Apart from that: calling accelerate with a friction and an acceleration of 0 does not make any sense.