Wire it to the other input.
Since you've scoured the software settings and I don't have said card, the hardware solution will solve this neatly.
I have a V-Gear 10 bit PCI Mpeg card installed with Aux line attacted internally to a Creative Audigy value sound card. Each time I turn on this TV card the record source of the sound card jumps to "line_in" source. I have to go to the mixer option to select "Aux" as the rec source each time I open my tv programe to watch and record programe. I was wondering if there is anyway I can force my sound card to record from the "AUX" source only so that I can schedule a recording task.