Ignition switched auxiliary/accessory power

I am in the process of installing a battery isolator for an auxiliary battery. I have an isolator from Sure Power, and instructions. The instructions read: "The E post of the isolator requires connection to an ignition switched source such that power is applied only in the ignition/run position. Be sure power is not applied when ignition is switched to accessory position. On most late model GM vehicles this may be one of the spare ignition terminals marked IGN on the fuse center." Ok...I've been over the fuse center under the hood and on the drivers side of the dash, and I do see a few fuses labelled IGN. However, I see no terminals that I can connect anything to. Has anyone located a switched terminal or connection like what I need, and can you tell me where you found it? Thanks.

take the under dash panel off and find a ign wire in the main harness coming from the key switch. then find a pink wire like a 10 gauge size and that should be what you need.