how to wire a dvc sub?

Yes,  diagram #2 shows the configuration that will put a 2 ohm load on the amp.  4 ohm impedance bridged across two channels = 2 ohm per channel.  That's a 2 ohm load and your amplifier will output at its fullest.  The output is identical to running 2 ohm loads onto each channel separately (as seen in Crutchfield's diagram).

Look at your amplifier manual, at the output ratings.  What is the output at 2 X 2 ohms (stereo)?  What is it at 1 X 4 ohm bridged (mono)?  Are they not the same power output?

What is the model # of your amp? (hopefully he wasn't referring to both pairs of output terminals on a mono amp when he said he's got a 1 OR 2 channel amp)

Let us know what the model # of your amp is and we can help you further...

Your link to the amp doesn't work. Here's one: http://www.ultralinear.com/index.cfm/Mobile_Audio_Amplifiers_Series_2/fuseaction/ViewProductDetails/ProductID/3,3700906

It claims 800Wrms x 2 @ 2ohms, but I couldn't find any info on fuse(s) size. How many fuses does it have? What ratings are they for?

But yeah, you'll want to wire each sub to 2ohms, and put one on each channel. BTW, 300 x 2 means 300 x 2 (600 x 1).

100amps worth of fusing, alright. Simple math (gotta love simple math) tells us that 100 (fuses) x 14.4 (voltage) = 1440. Take away about 35% for efficiency and you get 1400 x .65 = 936 watts.

That amp will give each sub about 468watts RMS. They call for 700Wrms, but in a ported box, they'll get loud enough for most (me, anyways!).

Oh, and I bet they sound WAY better than those MA's you had before. Try not to let these ones get gotten!