update: This driver has been updated for 3.12.32+

Download  the mt7601Usta.ko file.

copy it to your  /lib/modules/version/kernel/drivers/net/wireless folder.

scp mt7601Usta.ko root@rpiaddress:/lib/modules/version/kernel/drivers/net/wireless

 Copy RT2870STA.dat to /etc/Wireless/RT2870STA directory

 scp  RT2870STA.dat root@rpiaddress://etc/Wireless/RT2870STA

Then run sudo depmod -a

Then Add the below text to /etc/network/interfaces. Note that quotes around SSID and password are required

auto ra0
allow-hotplug ra0
iface ra0 inet dhcp
wpa-ssid "ENTER YOUR NETWORK SSID"
wpa-psk "ENTER YOUR NETWORK PASSWORD"

these instructions apply for 3.12.32+ If you want to compile yourself then compilation instruction are provided in the below mentioned blog. http://va3paw.com/2014/03/16/hsmm-mesh-on-raspberry-pi/#more-629

Instruction For previous version

Raspberry Pi MediaTek MT7601

Drivers for the MediaTek MT7601 USB Wifi adaptor.

3.10.25+
Linux raspberrypi 3.10.25+ #622 PREEMPT Fri Jan 3 18:41:00 GMT 2014 armv6l GNU/Linux

1. Copy mt7601Usta.ko to /lib/modules/3.10.25/kernel/drivers/net/wireless

2. Copy RT2870STA.dat to /etc/Wireless/RT2870STA directory

3. Run sudo depmod -a

4. Add the below text to /etc/network/interfaces. Note that quotes around SSID and password are required

auto ra0
allow-hotplug ra0
iface ra0 inet dhcp
wpa-ssid "ENTER YOUR NETWORK SSID"
wpa-psk "ENTER YOUR NETWORK PASSWORD"

References:

http://gowthamgowtham.blogspot.co.uk/2013/11/mediatekralink-wifi-adapter-in.html

http://www.raspberrypi.org/phpBB3/viewtopic.php?p=179845#p179845