7zip & @MyDocumentsdir ?

;===============================================================================
;
; Function Name: _Find_USBStick($label, $serial = 0)
; Description:: Gets the Letter of an USB-Stick by its Label or serial
; Parameter(s): $label : the Label or the Serial of the USB-Stick
; $useserial : if 1, search for serial, if 0 (default) search for label
; Requirement(s):
; Return Value(s): Success: Drive-Letter, Error: 0
; Author(s): Prog@ndy
;
;===============================================================================
;

Func _Find_USBStick($label, $useserial = 0)
$drives = DriveGetDrive("REMOVABLE")
For $i = 0 To $drives[0]
Select
Case $useserial = 0
If DriveGetLabel($drives[$i]) = $label Then Return $drives[$i]
Case $useserial = 1
If DriveGetSerial($drives[$i]) = $label Then Return $drives[$i]
EndSelect
Next
Return 0
EndFunc