Please help with antenna adapter

I'm installing a kenwood cd player in my wifes Quest ('95), has the "premium" stock sound system...

So, there appears to be 2 antenna connections for the stock unit, but the aftermarket unit only has one antenna input? I plugged one of the antenna connections into the Kenwood and everything works great except the audio fades in and out when using the tuner (CD player works great).

So, I've been reading that I need the metra 40-NI10 & 40-NI20 (kitted together, it's a 40-NI30) antenna adapter...

So, number one: Will this fix the fading of the tuner?

and number two: How on earth do you hook up this adapter kit? I've already got the 40-NI10, and I've looked up photos of the NI20, and cannot figure out how they are supposed to be installed!

My wife's been buggin' me to get this done, so any help would be appreciated!

-Mike