I'm sure a warm rice pack would work as well as a water bottle- the warmth helps relieve the pressure in the ear, I believe.
I lay the babe on my lap, sore ear up, and put the drops in. (watch out that the kid doesn't knock over the rest of the oil!LOL!) I make sure they are body temp (place the bottle of oil in a cup of warm water for a few minues). I massage around the ear until the oil goes in, sit the babe up and wipe away any excess. My 3yo actually asks for drops whenever her ears are sore- the warm oil feels good. We buy them from our local health food store, they also have mullien in them, which also relieves the pain.