Thanks for contacting Ask Extension. I was unable to locate any pressure canning instructions for leeks. It may be in part because the high temperatures associated with pressure canning would turn them to mush. If you still want to can them in chicken stock, you could follow the guidelines contained in the “Canning Soup” factsheet which is attached below. To prepare the leeks for canning, cut them into small pieces and cook them until they are almost done. The chicken stock would replace the remaining liquid called for in the recipe.  

That is a good question. The steps for preparing the broth would be the same, however, the canning steps for canning in cans would be different as opposed to jars. The University of Alaska Extension Service website has posted information on assembling the sealer for processing meat and fish in cans. Their publications tell you how to do it. Processing times differ depending on the size of the can, and those processing times also differ from glass jars. You might send a note to the Alaska Extension Specialist and inquire as to their recommendations. Because we do not have a research base of established processing times for cans for the home food preserver (other than fish and meat) from the University of Alaska, we can't provide any processing recommendations.