grab it at a junkyard! They'll charge you like five bucks for the cable, sensor, and bracket. And you'll get to look at how it's mounted so you know EXACTLY how to install it on yours!
I actually mostly succeeded at reverse engineering the OHC wiring pinout, I confused the temp sensor wiring for the CCD bus (was getting ahead of myself, CCD bus only went to the OHC on 97+ I believe!) and missed the purpose of the wire that controls the display brightness via turning the headlight knob. Other than that I got everything right. Cutting the headliner wasn't too bad, I threw a ton of masking tape on it and grabbed the tape measure and went nuts with a pen, then used a good sharp box cutter.
The dome there *is* for the keyless entry (which sucks, it's crappy line of sight IR) but there are five or six different wiring harnesses for the roof section of the cabin wiring and some of them don't have the connector for the keyless entry, or don't have the connector for the OHC. If the harness you get has the connector for the OHC the keyless entry cable will be long enough to reach to where it is with an OHC, otherwise it'll be only long enough to reach the front of the OHC, where the keyless entry without OHC is mounted. I am going to have to cut my cable and extend it when I get around to making my keyless entry work again, or I might just hide a two-meter ham radio, TNC, GPS unit, and microcontroller board up there and make myself a custom keyless entry/APRS "ham-lojack" system, haven't decided how much time I want to spend on it yet.