Can this be stacked with "the challenge"?
If you're referring to a Gold challenge or a Platinum challenge on AA, this promo is for something else entirely. You can earn status on AA through points, miles, or segments (or 1MM/2MM). The challenges are based only on EQP (points), which reward those who pay for the higher booking codes. This promo is for double EQM (miles). This may be an easier way to earn status for those who fly in deep discount economy fares, as it's basically BIS miles (min. 500 miles/segment for elites only).
This can go along with 3x RDM (reward miles, not elite qualifying) Boston bonus promo (BOS3X). This bonus applies only for direct flights between BOS-SAN/LAX/SFO. You'll end up with 3x the number of RDM you would normally get (a 200% bonus).