The instructions listed in the link from earlier posts I found have typos. Below are some corrected instructions that hopefully should get you on your way...
1. Download the file contained at this link: http://barkmunchers.com/dm1z/RT.tar.gz
2. Extract the files to a directory. Then open a console, navigate to the directory that you extracted the files to then run the following commands:
Note that for the last command above I used the option <uname -r>. This will copy the files to the current running kernel version. Make sure you are running the kernel that you wish to get the wireless running on...
sudo make install
sudo mkdir -p /etc/Wireless/RT5390STA
sudo cp RT5390STA.dat /etc/Wireless/RT5390STA/RT5390STA.dat
sudo cp ./os/linux/rt5390sta.ko /lib/modules/`uname -r`/kernel/drivers/net/wireless/rt5390sta.ko
Now edit /etc/modules to add the line 'rt5390sta' at the end
That should get you on your way. Hopefully that I didn't add in any typos myself.
sudo depmod -a
**Edit** fixed the <uname -r> with `uname -r`, Thanks frospeh for catching the error!