I actually went to try this for you. There's just about no way to do this without the Seeker looking like he's giving Optimus a scalp massage. There's limitation in the Seeker hands as well as (with most TF's) how the hands come together. Plus the backpack plug thingy (with the cab top removed) also doesn't help matters.
yeah, the hands are too small and restricted in movement to look like anything other than caressing prime's face.