Something that worked well for me:

I bought a handle with a crank. I took the crank off the handle. I took a
1/4 socket of a diameter just a little larger than the inside of the handle.
I turned down the socket wall so the socket just fit in the handle. I brazed
the socket in the handle, square hole up. Now I've got a crank which is, in
essence, a 1/4 socket. Add a cheap driver handle, and you have a very
convenient (ratcheting) handle on the router.

Dave Wetmore