Is possible to boot on PXE over a WiFi device?

At least one vendor has solved netbooting over Wi-Fi, but you're not likely to be able to do with with mix-and-match motherboards and Wi-Fi adaptors at this time.

You can boot MacBook Airs via Wi-Fi, as long as another machine on the network is sharing a Mac OS X install DVD via Mac OS X's DVD sharing feature. Since MBA's don't necessarily come with an optical drive or Ethernet adaptor, this can be the only way for some users to do a clean OS install.

Apple has built drivers for those Wi-Fi chipsets, as well as a UI for joining a Wi-Fi network, into the EFI bootROM on those models. As far as I know this is an Apple proprietary scheme, not PXE-based.

If your WLAN adapter doesn't support PXE, then no, you can't do PXE over wireless.

If your laptop has an Ethernet adapter, however, you can connect it to a wireless access point that can function as a bridge (or a dedicated wireless bridge). I've tried it myself, but it was too slow, I'd rather just move the laptop near an Ethernet switch/router.

Google for "iPXE". they claim to have support for booting off of a wireless network and even a web address. Also you might be able to flash their ROM over your wireless card's ROM instead of booting from the test iso you can download