You can use pXent_setvelocity and pXent_addvelcentral. for example;

Code:
VECTOR hold_target;
VECTOR my_kick;
.....
if (event_type == EVENT_RIGHTCLICK)
	{
		while(mouse_right==1)
		{
			
			if(!mouse_left)
			{
				
				vec_set(hold_target,vector(20,0,0));
				vec_rotate(hold_target,camera.pan);
				vec_add(hold_target,camera.x);
				vec_sub(hold_target.x,my.x);
				vec_scale(hold_target.x,10);
				pXent_setvelocity(my, vector(hold_target.x, hold_target.y, hold_target.z)); 
				
				
			}
			else
			{
				
				
				my_kick.x=10;
				my_kick.y=0;my_kick.z=0;
				vec_rotate(my_kick,camera.pan);
				pXent_addvelcentral(my, vector(my_kick.x, my_kick.y, my_kick.z));
				
				break;
			}
			wait(1);
		}
		
	}