I wanted to add a switched electrical accessory tap but, did not want to add anything under the dash since most add-on items will be under the hood or outside the truck so, here is my solution.

#1. Gather your parts; (Click on thumbnails for larger pic)

I chose to use a 3x6 inch black plastic project box from radio shack. It has a lid that is secured down by 4 screws. You may find something that works better, that's your choice.

Next, I chose a distribution block made by Buss. It has one power input and 6 fused outputs.

"Add -a- circuit" By Littlefuse

Now, for the relay. (This is an optional part but HIGHLY recommended!)The relay is used to cut the power to the distribution block when the ignition is off to prevent a drain on the battery. I used a standard universal 30 amp fan relay with four terminals. Your relay may be different. I chose this one because it fit the black box. (The relay shown is a 3 terminal but, looks essentially the same)

1/2 inch flat head machine screws and matching nuts and washers. (I used 2 sets)
1 1/2 inch flat head machine screws and matching nuts and washers. (I used 2 sets)

12ga wire (I chose red)
18ga wire (I chose red)

Small rubber grommets that fit the O.D. of the chosen wire

Large female spade terminals, at least 10
Large ring terminals, at least 3

#2 Putting it together;

Disconnect battery terminals. (VERY IMPORTANT!)

Disconnect main positive lead to fuse box

Loosen VX's fuse box from it's original mounts. This takes a 10mm socket or wrench. You'll need to wiggle the fuse box to get it loose from it's mounts.

The fuse box has a bottom that needs to be removed. On the front facing side (the side facing the battery) there are tabs that when released will drop the bottom. You will now be able to access the sides of the box and the wires.
The black project box needs to be mounted to the VX's fuse box. I did this by drilling matching holes in the rear (Side facing the firewall) of the VX's fuse box and the project box.

Don't bolt together as of yet, you have more work to do.

Mount the power distribution block in the black project box using the 1 1/2 inch screws and nuts. I put mine towards one end (the fender side) to make room for the relay and for clearance of the terminals on the distribution block.

On the short end of the project box that the relay is to be mounted, I drilled one hole large enough to accomodate the 12ga wire and two holes for the 18ga wire (I also used rubber grommets for water and dirt resistance so, you'll need to adjust your hole size accordingly)

Run your wires through the holes. on the ends that will be on the inside attach female spade terminals to accommodate the terminals on the relay.
Mount the relay in the project box. I fiddled with the mounting ears of the relay and used double faced tape.

Drill exit holes for the wires going to your accessories in the long side of the project box. (Side facing the firewall) I only drilled as many holes as needed for current accessories.

Bolt the two boxes together. Make sure to have the open end of the project box up NOT pointing towards the wire end of the VX's fuse box.

While everything is loose, connect the 18ga positive lead of the coil terminal of the relay (The one that activates the relay) to a switched fuse in the VX's fuse box by using the "Add -a- Circuit" or to a switched wire on the underside of the VX's fuse box, your choice.
Run the 18ga ground from the relay coil to the ground that is located just aft of the battery.
Run the 12ga lead from the switch terminal of the relay (The one that gets interrupted when there is no power supplied to the coil) to the main power lead of the VX's fuse box. The other terminal gets connected to the positive post of the power distribution block. (The one with the nut on it) There will be no power to the external terminals of the distribution block until you put a fuse in. That is why I chose this terminal block.

To power your gadget wire it all up then connect the power lead to a fused terminal and place the proper in it and away you go! When the ignition is on the block is active.

Place the lid back on the project box (New fuse Box) snap the bottom back on to the VX's fuse box and re-attach it to the fender well.

This is the way I did mine specifically to my needs, yours may differ some, none or allot. Use this as a reference only and by all means, take every safety precaution!