Use the numpad to the very right of the keyboard. 8(up), 2(down), 4(left), 5(right), then use mouse buttons 1&2 to go up and down chain(there default for primary and secondary attack).
Works great for me.
AMD Athlon XP 2200+ 1.8 ghz
WinXP SP2, DirectX 9.0c
1gb DDR of Ram
Sapphire Radeon X800 pro Vivo 256mb
80gb Hard Drive
SB Audigy 2 ZS/Creative Inspire 5.1 5300