Bookworm and Chilli Monster, thanks guys. I realise it is a fairly standard approach - it was just the particular one I happened to be looking at.
Flying the localizer backcourse makes perfect sense and I can now see that doing so would make it pretty easy - as the turn at the LOM is approaching intercepting the localizer is straightforward and thus would give an accurate outbound course.
What if there was no ILS? Would you still go to the trouble of intercepting a particular outbound radial from the LOM, or just make the turn and sort it out on the way inbound?
FFF, bookworm has kindly provided a link to the plate. It actually didn't work for me and I had to search for KSBN and then select ILS 27L. There is nothing special about this approach really - as bookworm says there are rules which govern the approach design but I was just curious about how to actually fly it in practical terms.