I am in the process of installing the a EVO-AUDT1 kit. However the keyport which the instructions say to remove the cable from the back of the keyport to attach the harness. Though there is zero slack in the cable even with the keyport free. How does one get any length in the factory wire cabling that is connected to the keyport in order to attach the fortin wire harness? From the attempts today there is no means the get the required length in the cable to complete the process. Pleae provide some quidance on this issue.