Can you save by buying Advantage flea control for dogs and using smaller dosage for cats?

I've been told Advantage Flea control has the same ingredients, whether it's
used for dogs or for cats. The only difference is that when you buy
Advantage for dogs, the measured single-application doses contain more
(because dogs are larger and require a larger dose). So if you have a
calibrated eyedropper to measure out the dosage exactly and information on
how big a dose to apply to your cat, theoretically you could buy a packaged
dose for a large dog and stretch it to several applications for your small
cat, couldn't you? Has anybody tried this, or or do you know of a site
where they tell you exactly how to do it?

-Garret Swayne
garret at garretswayne dot com