Some time ago I read an article someplace about modifying the brake system to stop a single front tire from spinning. It was not the modification using two levers but one that used a couple "T" joints in the brake lines with a dial that allowed you to have normal braking when set in a certain dial position and when dialed to the left would only allow the left front brake to work and when dialed to the right would only allow the right front to work. Where if a left front wheel is spinning you can apply the brake to only that wheel and transfering the power to be sent to the right front (and visa versa)

If anyone has some information about this setup please contact me or post a reply.