Replacing Pioneer Premium Sound System

[loosecannon]

I have a 98 ES300 with the typical burned out LCD screen. The untit sounds awesome but has limits. I am replacing it with an Alpine CDE-124SXM. I am using a Metra 70-8112 premade harness to "ease" in installation. I removed the old unit and am ready to install the new one. My question is, the Metra harness comes with four RCA plugs for the speaker connections. The Alpine has the four speaker leads plus the usual four speaker grounds. On the 15 pin connector, it looks like each speaker is separately grounded (white wire) I thought I knew something about this stuff and now I am just thoroughly confused. Can anyone help me with the proper connections to make?