6 Gear Shifter

Hi,

I've looked online and can't workout what is best to do...

I have ordered a 6 gear shifter than i want to use for the full 12 gears but i only want to have to change gear 6 times - i dont want to use the high/low button on it.

Without installing a 6 speed in game is there a way i can use a 12 speeds with only 6 gear changes? Does mapping the gears to only even work or is there a better suggestion?

Many thanks