Doesn't matter what birds you have, non usually like to have things done to them
So... the easiest way to do anything to birds that don't like you touching them .. is wait until they roost at night time, go to sleep, give them an hour.
Then go into the coop with a small pen light.. or a light with red paper over it to give a red light hue, and put the cream, jelly or what ever you decide to put onto the comb
If you need to do other things... wrap the bird in a towel and take them inside and stand then on something that they can't slip around on and do what ever you need to do
Do not make a lot of noise.. none is better, keep bright lights down to a minimum, and do what you need to do quickly and take them back to the coop and place them onto the roost and make sure they are balanced and leave them to sleep
Do not go and put a light on in the coop waking up all the birds
Do not joke around laughing etc, it will wake and scare the birds