I believe the Broadcom accelerator card should work in a true Mini PCIe slot. Not a Mini PCIe
SSD slot, and not a WWAN/cellular slot (frequently WWAN slots are USB only). WiFi slots tend to be true Mini PCIe.
Also, mini PCIe slots come in full and half height. Newer laptops/netbooks (like the 1012) tend to use half height WiFi cards. Older ones (like the Mini 9) use full height. The Broadcom accel. card is available in both sizes.
A half height card will "work" in a full-height slot, you'll just have to be creative to secure it. A full-height card will be a difficult fit in a half-height slot.
I hope this info helps someone.
As one final caveat, some laptop manufacturers cripple their WiFi slots, to force you to buy upgraded WiFi cards from the manufacturer, instead of eBay/newegg/etc. I expect the Broadcom card won't work in those laptops. I don't think Dell does this.