I've never done it either but appears there isn't enough room to slide the solid part of the steering cable out of the steering tube at the engine without bending it. I don't mind bending the cable I'm taking out but I would also have to bend the new cable to get it in. I'm sure this is not the orginal steering set up or engine on this boat. It's a 1971 Starcraft with a 90 HP Mariner under most circumstances I don't this it would be necessary to remove the engine to replace the steering cable.
Starcrafts were great for that problem,you usally can remove the bolts and slid the engine on the transom that will save disconnecting the wiring harness and control cables
Thats what I did, hoise the engine up a little to take the weight of the trans and then slide the engine over to the left and pull the cable out, if you pull the engine off the trans you may bend the cable when you take it off and put it on... DID THAT TOO