No need for command line. Just edit config.txt and you can use my config. I get 26,7 MH/s with modified BIOS:
-pool ssl://eu1.ethermine.org:5555
-wal YOURWALLET.%computername%
-amd
-clgreen 1
-astats 1
-gbase 0
-mt 2
-acm
-leaveoc
-altinit
-powlim -20
-tt 64
-tmax 66
-fanmin 65
-fanmax 95
-fcm 2
10x for the settings, can you explain which of these make 4Gb cards to work?