Thinking about the people who might read this I dont want to have people trying something like this if they are completely without any occult experience. This cannot be a 'colour by numbers' type application and nor can it be done just as quick. So leaving the demon selection part on hold for a while I'll look at the 'delivery' method of bonejacking.

Rules apply to demons as well as us, if a demon turns up at your house unannounced it is obligated to leave on your say so although you may have to be a bit forceful with prayer/ritual to encourage them to leave. However with an atheist as they deny themselves all use of prayer and ritual (though I believe they would use such things in private if it means preserving their body and lifestyle. Put it this way, if you go up to an atheist with a revolver, point it at their head, cock the hammer any money says theyll scream for Jesus to save them). So if demons turn up at your house and did not 'reside' in it before you moved in they are obligated to leave on your say so and will unless you give them permission to stay or refuse to boot them. Maybe you know the term 'bless this house' which you may see sometimes on a wall hanging with a reference to Jesus, apart from the cheap junk ones from china it is an asking for the house to be protected from all malevolance both human and demon (if you want to get one go to a catholic church shop, the priest will bless it if you ask).

So one turning up in your place is one thing but one being invited in is another whether deliberately or inadvertinely. And this is the key, one must be able to get a sigil within their residence and other places where an atheist may spend a considerable amount of time (workplace? nah Im thinking swingers club..), but you would have to get them to take in such a thing by their own free will. Suggestions can be something like sending a letter or card which they are most likely to keep longterm, but even better would be an item that can have a sigil either placed within it or engraved on it. This is why you should have some sort of knowledge of your target, if they like collecting figurines or something similar you could somehow place a sigil within it and on top of that you can 'charge' the item much like a battery. As demons are bound by planetary/astrological/mechanical days and hours; if you have picked a demon that say.... operates at night... then the atheist will most likely be asleep when the demon comes in. And being an atheist will have no protection if the demon attempts a bonejacking.