Hi Viola,
I did post a few link back some pages that I have found to be good sources of info, but nothing really as an 'online' how to.
We have not looked into any spray methods, as we just don't turn over enough birds to warrant it. Most of what I had read said it should be injected (I know there are some places that spray while the chicks are on a conveyor).
Injection does have some options, if you are turning over a considerable amount of birds, you could look at a gun
http://www.bellsouth.com.au/health/vaccines.asp to make life easier for more birds. The other options are a needle in the neck, pointing away from the bird (towards the body) Just lift the skin away from the neck so it forms a little 'v' shape and inject under the skin, not into the muscle.
I know a lady who does not like that way and she injects it into the foot as there is less chance of something going wrong. I have not found a link just yet.
There is also in 'in ovum' method that seems to be used in the commercial industry, Oz has also adopted this method (without vaccination I think) to assist in his hatch rates. Basically, a hole is made in the air cell around Day 18-19 and the vaccination is administered while in the shell.
I could post the info I have about the vaccine we use. I was sent a page of info from the supplier, I typed it out as it was a bad photo copy, but happy to share it. Sorry I could not be of more help.
and just in case anyone wanted the answer.....