@jecilop,
Create a windows .bat file using your text editor of choice containing a one-liner something like this (assuming you're using calibre 64-bit):
Code:
"c:\program files\Calibre2\calibre.exe" --with-library "d:\calibre\MyTestLib"
where the
red bit is the Windows path to the directory containing the calibre library you want.
Edit: WAG, in this context, "Wild-ass guess", I think