For lacing on the feet, the easiest way *seems* to be to have a few rows that go across under the foot. With "lugged" soles, this is easiest since the lace stays mostly off the ground (and what I do with my sabatons). The biggest thing to getting the chausses to sit properly over the feet is that it needs to be trimmed so it won't hit the ground when being worn. Put the chausses on, get them in the right position, and ask your dad to draw a sharpie line all the way around both feet, about one ring height up from the ground. Then trim them to fit, and they *should* lace and sit better; I did the same thing with my chausses when testing the lacing, but need some assistance in getting mine marked to trim down.
I think your dad will be able to help as long as you tell him what to do, or have him read it here. I talked with him a bit at Days of Knights, armor is not his thing but the little bit that I tried to explain with lacing to the C-Belt he seemed to understand. Marking the rings to cut should be pretty easy, although it will be a little time consuming (15 min maybe?).