Jeff,
Talk to a heavy towing company as they pull axles on a regular basis. It might just be cheaper to hire them to pull the axle than to buy the tool for the single use.
There are pliers made specifically for removing those split axle cones. One jaw is pointed to spread the cone for removal.
Other Jeff.
I too had to add a power feed to this plug on my 1586 to power my 6601 combine. I put an inline fuse on it as well as running the wire inside some plastic tubing for protection against shorting out.