Killians is a lager, which is why it came with the lager yeast. If you can follow the fermentation and lagering schedule, Use the lager yeast. You could do this with a swamp cooler (simple tub of ice and water that you refill every day or two) but I would suggest reading up on it thoroughly first.
The easy route would be to use us-05 dry yeast, and keep it as cool as you can, between 65 and 70 degrees F. This, while not a true lager, will be as close as you'll get with ale yeast.
Really, you can use any yeast you want. If you want it to taste like Killians, use a neutral ale yeast (05, wlp001, wyeast 1056) or lager yeast. If you use another yeast, it will taste different, but not bad as long as you keep it within the temperature range for the yeast. Just make sure you understand what flavors the yeast you're using impart before you use it.