Mommy Points details the upcoming US Airways ‘Grand Slam’ promotion. You can’t register for it yet, but the offer’s FAQ page is up.

The offer will run from September 14 through November 14, and will eventually be detailed (with registration available) at usairways.com/grandslam.

This annual promo stretches a baseball analogy where various partner activities are considered ‘hits’ and the more hits you accumulate, the more bonus miles you earn. For instance, 4 ‘hits’ earns 3000 bonus miles while 8 hits earns an additional 7,000 bonus miles (on top of the 3000 that were earned after 4 hits had been completed). So 8 partner activities is 10,000 bonus miles.

Lots of folks will start to figure out the cheapest ways to get eligible partner activities, and I’ll certainly report on several of those here.

If you have a US Airways credit card and earn points with it during the promotion period, you’ll get a hit. If you transfer points from a hotel program to Dividend Miles, you’ll get a hit — one hit per hotel program you transfer from. They’ve made it a little bit restrictive, Starwood Platinums can no longer transfer over just 1 point, you’ll have to generate a minimum of 850 US Airways miles for the transfer to count.

If you credit your hotel stay to Dividend Miles, you’ll earn a hit, up to 6 separate hotel stays (with the same chain or different chains). But again there’s a minimum earning threshold, really ultra cheapie stays earning very few miles won’t count. Similarly, you can earn 6 credits for car rentals.

Downloading the ‘Dividend Miles toolbar’ and completing 3 mileage earning searches earns a credit. So does sharing miles from your account, or receiving miles (you can earn only one credit from doing so, not one for each). A mileage transfer from another program into US Airways via Points.com will generate a credit, too.

Shopping through the US Airways Shopping portal earns a credit, and so does shopping via the US Airways Skymall site.

Earning the top-level bonus will be restricted to US Airways elite members. If you’re going to get there it could be worth buying ‘trial’ preferred status before the 40th and final credit posts from the promo.

Anyway, this is all rather ‘inside baseball’ at least until the promo goes live which should be shortly.