Rather than use clamscan from the command line - I would like to use clamwin from the command line but pass it a parameter of what disk to scan so that it comes up, opens its window and starts scanning the disk. Is that possible?

You can use the command line switch that is used by the shell extension :

Also, if you don't want the pesky black command line window, you can use this line in a batch file and the command window will go away as soon as clamwin is launched:

start /d"c:\program files\clamwin\bin" clamwin.exe --mode=scanner --path=%1

Excellent!

Thanks!