I have had to bridge starter wires to get cars going before.
I lay under the car and bridged the terminals with a screwdriver with the key turned to on.
But if you want to do it safer then your idea will work.
Just make sure you use some pretty fat wire and a suitable switch or your wires and switch will burn through.
You need to bridge the two large terminals on the started solonoid, which is the smaller cylinder attached to the starter.
DO NOT ALLOW THE STARTER TO RUN MOAR THAN 10 SECONDS
I TAKE NO RESPONSABILITY IN GIVING YOU THIS INFO
TRY AT OWN RISK
Pics...
This one shows the solonoid...
This one shows the two terminals on the back of the solonoid
Ignore the wiring in black, I have added some red wire to the pic, you need to do the red wire.