Run Setup from the command line with the following parameters:

/SILENT, /VERYSILENT
Instructs Setup to be silent or very silent. When Setup is silent, the wizard and the background window are not displayed but the installation progress window is. When a setup is very silent, this installation progress window is not displayed.

/DIR="x:\dirname"
Overrides the default directory name displayed on the Select Destination Location wizard page. A fully qualified pathname must be specified.