Part 1.
I am on the path to making a (ram arm travel) limit switch system for my st 1000 Raymarine tiller pilot and it is fun!
By trawling the net and referring to the systems that Wongaga has suggested I have identified 4 basic approaches.
1. micro switches activated by rods and sliding cams.
2. micro switches attached to the parallel guide rods and activated by end stops.
3.micro switches located at ends of travel positions and activated by the traveling fitting on the parallel rod.
4. Inward stroke micro switch activated buy a length of fishing line.
They all do the job but I am put off each system for a different reason.
1. micro switches activated by rods and sliding cams. This is really well thought out and robust. Steam engine tech. However sourcing 3 or 5 mm square brass rod is not that easy to get hold of and the unit is bolted through the housing. Something that I just don''t want to do.
2. micro switches attached to the parallel guide rods and activated by end stops. With a drill press and taps this would not be difficult. The location of the micro switches could be very accurate. But, I don't like the idea of drilling into the parallel rods and I don't really understand the function of his added board.
3. micro switches located at ends of travel positions and activated by the traveling fitting on the parallel rod. This installation is the scariest. This guy attached the micro switch to the board with glue and set screws. Then when that didn't work attack the board with a Dremel rotary saw. No thank you. 
4, Inward stroke micro switch activated buy a length of fishing line. Just too easy for the line to get snagged up on something.
What I want is a drop in unit. Make it up on the bench, fit in with original attachment screws and plug in. I would like to come up with something that anyone can make with limited tools. These are the patterns that I have been through so far. I have a working prototype and waiting to see how Wongaga made his.
Cheers
gary
Part 2
My prototype is a base which houses the micro-switches and a sliding cam plate which activates the outward stroke switch. Both base and the cam plate are positioned by the screw lugs in the st 1000 housing. These lugs are 6mm at the top tapering out to 8,5 mm lower down. This is a photo of the base template and some clear plastic that I used as a mock up. The right side is the motor end and the notch in the left side is the recess for the outward stroke switch. The lower edge is shaped to follow the curve of the housing. 
In the next photo you can see the mock up dropped over the screw lugs. At the bottom of the photo you can see a black piece of Laminex / Formica with holes. That is the finished (at this stage) base. The small countersunk holes are for mounting the base supports which in turn mount the micro-switches. 
The next photo shows the base supports. I made this from clear plastic so I could see what was happening under the base in operation. The interior of the housing is not flat. It has an undulation, so each wooden support is a different size. The one on the motor end is a support and the mount for the inward stroke switch. The centre one is simply a base support to prevent sagging and the compass end one is a base support as well as the mount for the outward stroke switch. 
The next photo shows where the electrical components mount on the base supports. 
Here is the base dropped into position with the switches and diodes fitted.
Cheers
gary
Thanks for the advice Woko. Now I will be continually looking over my shoulder.
Part 3
The sliding cam plate is made of 3mm plastic used for sign making.
Any 3 mm plastic material will do.
The base is 1 mm Laminex, so the total thickness of the mechanism is just over 4 mm. You need it to be this thin to be below the traveling end fitting of the ram.
The sliding cam plate has three elongated holes that locate it on the screw lugs and allow it to travel. The trigger end is tapered down to 5 mm to allow it to pass a lug. There is a 2mm x 12 mm setscrew on the end of the taper as a trigger. I stripped a bit of wire and used the plastic as a sheath over the trigger. There is a 6mm x 6mm cutout where the micro-switch roller rises. There is a cam ramp filed on the under side of the cut out to allow the roller to function smoothly. I have fitted a 3mm x 20 mm setscrew as a retainer for the return spring. The spring is 4mm x 23 mm and I bought it at the local hardware shop. As the trigger is pulled forward the rear of the the sliding cam plate can rise and this can lead to a jerky movement, so I have made a small wooden hold down plate that fits on a lug. This is sanded down to be 0.5 mm thinner than the lug height, so the case can be screwed closed and the hold down plate will not be pinched.
Cam plate with wooden hold down plate, return spring and trigger.
Cam plate cam ramp detail 
Micro-switch roller location detail, Return spring detail
Alternative return spring system 
Trigger detail
Installed with wooden hold down plate detail.
Complete installation of sliding cam plate
Gary
