In a pinch, you can make one by grinding down a socket. I think it was 15mm? Don't quite remember, and can't read the number on my pic.

Easy for removing, more tricky for installing. You basically have to make sure the inner bolt doesn't spin after torquing it down correctly. With the Honda tool, you can hold the inner bolt with a hex wrench. With this one, you have to visually make sure it doesn't spin, and correct it if it does. This method worked great for me, although I wouldn't admit it publicly