The answer to this question (whether it is the correct answer or not I do not know) was explained to me by my high school math teacher. Technically speaking, (in his opinion), "ki-LO-meter" is a common mispronunciation and it should, in fact be: "KIL-ometer". However, in his opinion a "ki-LO-meter" is a legitimate word IF you were actually referring to a measuring device used to measure a kilometer, much like a "micrometer" pronounced: "miCROmeter" is a type of caliper used in extra-fine measurements, or as you mentioned, various other "-ometer" measuring devices.

Therefore, in summary, (the way it was explained to me):

KILometer and kiLOmeter are both acceptable pronounciations.. BUT

KILometer = a distance of 1000 meters
kiLOmeter = a (theoretical) device used to measure kilometers

Does that help?