Open up a shell and type:
wget http://rt2x00.serialmonkey.com/rt61-cvs-daily.tar.gz tar xvfz rt61-cvs-daily.tar.gz cd rt61-cvs-* cd Module make
Then, as root, type:
make install rmmod rt61pci 2>/dev/null modprobe rt61
You also need the following each time you want to use the device in monitor mode:
iwpriv <interface name> rfmontx 1
For the above command, first make sure the interface is down. You can bring the interface down with “ifconfig <interface name> down”.
NOTE: This will download the Enhanced Legacy version of the driver. Recent kernels include the Next-Generation version of this driver (called rt61pci). The rt61pci driver is untested, but probably needs no patch besides the usual mac80211 patches.