i dont know how to do this part.....
start cgminer with the following arguments:
cgminer-nogpu.exe --icarus-options 115200:1:1 --icarus-timing 3.0=100 -S COMx
for more than one device: cgminer-nogpu.exe --icarus-options 115200:1:1 --icarus-timing 3.0=100 -S //./COMx -S //./COMy
I'm using cgminer 3.1.1 and it worked on Windows 7 with instructions like the ones af_newbie provided.
Once I had downloaded and installed the driver (
http://www.silabs.com/products/mcu/Pages/USBtoUARTBridgeVCPDrivers.aspx), I plugged in the Erupters. After a moment, I could see my 4 miners in the device manager. I've never used Windows 8, but under Windows 7 my 4 Erupters come up as this:
Silicon Labs CP210x USB to UART Bridge (COM3)
Silicon Labs CP210x USB to UART Bridge (COM4)
Silicon Labs CP210x USB to UART Bridge (COM5)
Silicon Labs CP210x USB to UART Bridge (COM6)
Then using those com numbers, I created a shortcut on my desktop with the following target line:
C:\cgminer\cgminer-nogpu.exe -o
http://pool:port -u username.worker -p password --icarus-options 115200:1:1 --icarus-timing 3.0=100 -S //./COM3 -S //./COM4 -S //./COM5 -S //./COM6
Works great. Hope this helps.