*UNPLUG THE PLATE AMP AND WAIT 30 MINUTES* Last thing you want is some capacitor inside the amp potentially killing you.
Step 2:Remove the plate amp
Disconnect any wires that are in the way.
You want to avoid removing the driver because it's just more work and you can scratch the front of the sub.
If possible identify the speaker wires coming from the driver and cut them near the amp end of the wire. You're going to reuse these wires and re-solder them to a different part of the amp.
Identify where the binding posts pop through the other side of the PCB board. Doesn't matter what binding posts you use, they're all passive because no amp is hooked up.
Solder speaker wire to the leads. Easier done with a second pair of hands to hold the wire in place.
If you're subwoofer is ported you MUST buy an amplifier with a configurable high pass filter. The best way to do that is to buy an inuke nu1000DSP. If you have a $1000+ sub you might want to buy a NU3000DSP for the extra power. If you have a sealed subwoofer you don't NEED a high pass filter and could get by with a DSP-less behringer inuke, but having the flexbility of a DSP amplifier is worth the cash if you like tinkering at all.
Figuring out where the box is tuned is difficult, you can safely do a 24db butterworth at 20hz (lowest you can go on an inuke) and work up from there. I will post a guide soon on how to use the behringer software.