It's a bit problematic. I make my own strings and have been using 8 strand in either 8125 or Dyna-10. Currently with my Carbon Express nocks I just serve normally with a .024 braid and the nocks snap right on and don't need any modifications. With Gold Tip arrows and nocks I have used 1)- tape, like masking tape, under the serving in the nock area. Works OK but doesn't last as long as I'd like. 2)- Dentil floss to build it up after it's served but, again, it doesn't last too long before it gets frayed - the up side is that it's easy to replace. 3)- build up the area with normal string material after serving - same problems as dentil floss only it might last a bit longer. 4)- I have tried adding extra string material under the serving but it's a bitch to keep it all lined up while you serve but the biggest problem is that the string is no longer round.
I think the best solution might be to do your best with the string and serving and then modify your nocks to fit properly.
One other thing, make sure you have both a top and bottom nocking point. I recently have tried the method posted on here by McDave (I think) and it works great. Make them a little closer together and they will also capture the nock real well.
I'm interested in what other solutions guys have found to this dilema.