I don't know physics at all but couldn't you make the snowman a non physics object then when the player hits it with a c_move change it to a physics objct and apply the players move vector as a force. I'm sure some one who knows the physics engine could tell you more.

action player()
{
stuff here...
c_move(ect)
if(trace_hit)
if(you !=null)
if(you==snowman)
you.become_PH_object=true;
vec_set(you.focre,my.move.x);
}
action snowman_act()
{
var changed;
while(my!=NULL )
if(my.become_PH_object==ture && chagned==false)
changed=1;
make_me_aPH_object......
PH_force_of_some_type=vector(my.force)

}

you fallow...
Hopefully some one that knows this stuff can help more
Malice