This is an old revision of the document!
p54 is the mac80211 stack dependent wireless driver, it supports softMAC Intersil/Conexant Prism GT, fullMAC Intersil Prism GT, as well as Intersil/Conexant Prism GT USB dongle based chipsets.
Not to be confused with prism54 driver which is dependent on the legacy ieee80211 stack, has injection support but only supports Intersil Prism GT fullMACs.
Currently as of writing, there are no patches for injection and it is generally recommended for the user to have kernel version 2.6.28 or better.
More information on how to get the driver working can be found at http://wireless.kernel.org/en/users/Drivers/p54. If you have difficulty understanding what filename should the firmware be named as for it to work, once you plug the device in, check the last few lines of dmesg or /var/log/messages for information.