To the original poster, how high up are those nest boxes exactly (inches high?) and what breed are you working with,
and standard size or bantams? The ladder suggestion seems like a good plan although for one of my nest boxes they do hop from an overturned bucket into that box.
You can use the shavings, no problem, what I do in my nest boxes is an inch or two of shvings and then some grass hay on top of the shavings. The shaving cushion the eggs if they get too aggressive in their nest bowling and dig all the way down to the wooden floor of the box. But over the years I have found that they do love to sit and create a little nest while waiting for the magic to happen and shavings are just not formable for hens. If you can't find grass hay you can try grass clippings, to the poster in the desert, I would go with paper from the paper shredder. I have read in here that people do not suggest straw since the hollow tubes of straw make excellent hiding places for mites. So if you don't have straw now, don't buy straw, use an alternative.
You really don't need 'help' getting your chickens in the nest boxes, since the eggs are in the reproductive systems and they will not drop down and out of the pullet until they are completely formed, so there is no reason for the girls to go into those boxes until the egg is 'there' , knocking on the door to get out. Think of it like a dog going to have pups, she won't be sitting in her kennel dreaming of the pups until her body starts to change and her temperature drops and that message from mother nature tells her, "Get in the kennel and start 'nesting' since you have a pup heading for the birth canal"
A chicken is basically the same, they may already know what those areas are for, it's just that their bodies are not ready yet so no reason to sit around when there's real chicken business to tend to.
To the poster that said that his chickens have preferred to sleep in his nest boxes and have encouraged this with shredded paper, you Will have Poopy eggs. If the chickens are still not laying, you are lucky, you still have time. A nice big board to cover the nest box holes needs to go up about an hour before sundown and block those chickens out of there and force them to go figure someplace else to roost ASAP! Then remove the board each morning when you unlock your chickens for the day just in case they need to start laying.
Golf Balls seem to be the best hinters for chickens since they also cure the egg peckers from pecking eggs.
To the poster who wrote they only made one next box, yes it IS true, there IS only one magic nest box BUT, if you get one hen go broody and if she is the alpha hen, she may plug off that one box from everyone else so even though it may seem a waste, a back up nest box is always a great thing to have available.
Also, LOL about the poster that wrote the comment on the paper cuts.
And lastly, the person that wrote 'Mate' the chickens, you may want to clarify that statement because maybe not everybody would be totally clear about what you wrote or meant and that could be an extremely bad thing. Also, the egg does not just happen and fall out one day because the chicken was running around the yard not realizing it was a chicken, it is in stages and forming for quite some time, starting very small and growing in size until it is completely ready so Mating doesn't make an egg just appear, it is when the egg is full sized and ready to be released that makes an egg happen. I have had roosters actually breeding pullets before an egg was ever ready to be laid. It's the same theory as a girl does not have to see a cute boy to have a period, it's just going to happen when her body is totally ready and not before.
Sorry for TMI for anyone offended.