Credit goes to original author, I just modified it so it worked for me on bt4 final.

1. Download the precompiled kernel image and headers from here: RapidShare: 1-CLICK Web hosting - Easy Filehosting

2. If they were downloaded to your ~/root folder do the following:
cd ~/root
sudo mv linux-image-2.6.33-wl_rt3070_i386.deb /usr/src
sudo mv linux-headers-2.6.33-wl_rt3070_i386.deb /usr/src

(aka just move the files to you /usr/src dir)

3. cd /usr/src

4. sudo dpkg -i linux-image-2.6.33-wl_rt3070_i386.deb

5. sudo dpkg -i linux-headers-2.6.33-wl_rt3070_i386.deb

6. update-initramfs -c -k 2.6.33-wl

7. update-grub

8. go here: Ralink corp. and download the following file: Firmware RT28XX/RT30XX USB series (RT2870/RT2770/RT3572/RT3070)

9. Again, assuming the file you just downloaded is in your root folder type the following:
cd ~/roo
sudo mv rt2870.bin /lib/firmware

(aka move file to your /lib/firmware dir)

10. Finally edit the following file:
/etc/modprobe.d/blacklist.conf (or blacklist cant remember)

and add blacklist rt2870sta to the end. Save and exit

11. When you reboot, make sure to choose the kernel you just installed (2.6.33-wl) when grub prompts you to choose which kernel it should boot.

12. Finally, make sure networking is activated and type the following: sudo modprobe rt2800usb

13. airmon-ng start wlan0 && aireplay-ng -9 mon0 to try out your now working alfa beast.