92 Ford explorer: SPEEDOMETER

I just purchased a Haynes book on my explorer and I am about to tackle this project. If I read right, it states that I need to remove the neg. battery cable, remove the instrument panel, and then the inner panel to get to it. I also think I found the cable that leads from the transfer case(near the transmission pan)to the speedometer. I checked at my auto store and they said its a cable that goes to the speedometer. Has anyone done one of these before and can give me some advice/pointers? Thanks for the help.