Get a different fuse block, I wouldn't run that one, Sorry, but they are kinds cheesy. I would get one like this:
Summit sells them for around $7. One of the terminal strips goes in each side. This way, you can cut one terminal off of each strip, and use that as the constant 12v in (at say, the top), then when the fuse is plugged in, it carries power to the opposing strip. There is the constant power source for the one wire.
For the three ignition wires, use the strip the has three terminals on it and run one power wire to it (* more on this wire later) and plug it in the same side that the constant 12v wire is in. One the other side, cut an separate the other three terminals so you have three individuals. The three ignition wires from the harness will go there. (Run short pig tails to the terminals before plugging them in to the block, THEN connect the harness wires to the pigtails.)
* For the ignition-on wire, use a relay for this. I ran a large gauge wire from the alternator to my fuseblock. I split it at the fuse block.... one to the 12v constant, one to the relay.
I'll find some pics to post up for you. I think I even drew a diagram somewhere. I'll be back in a bit.