How do you properly join cat5 wire

I think you are confusing that with a telco splice (UY butt splice, etc.), which certainly isn't allowed.

That junction box is almost exactly like a cross connect block.

The way I'm reading this is, you have 2 wires running to the control room, one from a router, the other from the PC,, and you want to join them in the control room? If this is what you are saying, then you need a cat5e patch in the control room. The run from the router would get punched down, and the one from the PC would get an RJ45 and plug into the front. One suggestion I would offer though, is, instead of running the wire to a PC, you might run it to a wireless router within range of the computer area. This was you only have to run one wire, and don't need to worry about adding for future. Practically all computers have wireless capabilities now. Just a thought.