I have found a solution to use this card.
It uses commercial
software which loads the Windows driver.
I downloaded and installed the software yesterday and my WPC54G card works without any problems.
Since linksys does not support a driver for Linux I find the $14.95 not too bad to have my card working.
I cannot post the URL, however do a search on linuxant driverloader.
This message is not an add for linuxant. I am in no way affiliated with linuxant.
I am placing this message because it solves a problem.