I use cgminer and MSI 7950 to mine Litecoin, after a lot of test, the device can get over 550 kh/s , here is my configuration of cgminer
cgminer --auto-gpu --gpu-engine 960-1020 --scrypt --thread-concurrency 24000 --intensity 20 --worksize 256 --url stratum+tcp://stratum.give-me-ltc.com:3333 -u *.* -p *