You need a longer bow line, long enough so that the bowperson can hang onto the bitter end and snag the cleat after the springline has caught and you have throttled up to snug the gunwale to the dock.
1. As the boat noses into the slip, Bowperson drops springline over dock cleat.
2. With springline away, Bowperson takes bitter end of bow line in right hand and working coil of bow line in left hand.
3. When boat tugs against springline, helmsman throttles up and snuggles boat toward dock, signals bowperson to snag bow dock cleat.
4. Receiving signal, bowperson tosses working coil onto dock and, hauling on bitter end, belays the bow, preventing the nose from swinging away from dock.
5. Helmsman shifts to neutral, throttles up to clear carbon (diesel) or shuts down engine (gas) steps off and cleats stern line, then walks forward and ties off bowline.
6. Helmsman returns to adjust and tie off stern line and shut down engine.
7. Both take bows acknowledging awestruck dockwatchers.
All of the above assumes that fenders have not been forgotten, the springline snagged the cleat on first try, boathook did not get snagged with springline on cleat, helmsman and bowperson both understand what signals mean what, and the wind and waves are in your favour.
You can see our springline at the midship cleat and our fore and aft lines here: