Hypothetically, if I decided to upgrade my D440 from an 8-speed to a 24-speed, are there any specific components (triple crank & front derailleur) that would work best?

I know that the SRAM website shows that the Truvativ Firex 3.3 crank is compatible with the SRAM X.5 components. However, the specs indicate that it compatible with a 9-speed chain? Will this crank work? Are there better alternatives?

What about the front derailleur? Am I safe to assume that the SRAM X.5 would work? I believe that it would require a shim to be mounted to the frame.