Used a piece of hard wire to lock it open. Use just the rear parachute cord. This is on the Dual Classic seat. No matter how well you lube the thing it keeps locking closed. The hell with that.
Not sure how ya do it but mate of mine made one for my roadstar yamaha years ago with fishing line and a trace linking the fishing line to a keyring around the latch under the seat, the keyring sat outside the seat and the swivel and trace hooked the latch at the locking mechanism.
I thought many times about replacing the key lock part on the side cover with a push button. All that keyhole does is give me a place to forget my key when I get under the seat since I use my keyless ignition to start. Have on more than one occasion rode somewhere after getting under the seat and happen to see my key and fob dangling from there!!