I think this is how it's done!
To cut a housing mark out with a knife and then use a chisel to create a shallow v-shaped groove along the line. Then, using this groove as a guide, cut down to depth using a backsaw. I also chiselled the bottom limit of the housing on the edge of the piece.
Use a chisel to remove the first part of the trench, then set the router to a very shallow cut. I draw the router towards me, shaving with the grain or chipping across the grain (I have been using softwoods for practice). The sides of the trench guide the blade. Lower the blade of the router and repeat until the depth is correct. It's pretty quick, but you need to be careful with the depth.
As for sharpening, I have done that by eye/hand on the edge of an oilstone - it doesn't seem to be too critical. For the V cutter you can make a small holder.
This is how I worked it out for myself - there may be a 'right' way I haven't sussed yet - and if there are any helpful hints I'd like to see them as well.