Run a line that's just like a preventer, from the cockpit to the bow and then outside everything back to near the cockpit (instead of onto the boom like when it's used as a preventer). Put a loop at the end of the line, using a bowline or splice or anything.
Then as you approach the slip, loop the line on a cleat without leaving the cockpit and pull in the slack. Taa-daa! You have a spring line in place. Keep a little power on with port rudder to force your boat up against the dock.
Haven't tried this myself. I'm thinking about something similar for picking up a mooring single-handed. Haven't tried that yet either, by the way.
Fun fact #2484: In my avatar, that's DavidPM at the helm of my boat.
Bland, non-political statement goes here.