we used to do this on rx7's at my old work, i would like to do this also... we just used to use very heavy wire (stereo looking wire) and cut to right length and attach spade connectors and bolt to old terminals unfer bonnet and obviously run under carpet to boot.One of my next jobs will be to move the battery into the spare wheel well, then I can remove the battery tray too. It should look a lot tidyer in the engine bay with the tray removed.