I'd assume he did the following:
For SkarmCents, he first found 416 x 334 = 138944. Then, for every Pokemon, he calculated Atk x HP / 138944.
For BlissCents, he first found 714 x 306 = 218484. Then, for every Pokemon, he calculated SpA x HP / 218484.
For all your Pokemon needs (and more!) including: the Defensive EVs
applet, the Probabilities of Breeding IVs in Pokemon
applet, and the Ratings of Pokemon Base Stats
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. And also the IV to PID