A. Pronk,
You say shares can be created with WMI
I think it is in the script Fredu posted. Don't you think it will work? I presume he should just run (most of his) script as administrator.
This is a quote from his script:
Code:

Function CreateShareFolder($ServerName,$ShareName,$SharePath,$Discription)

$FILE_SHARE = 0
$MAXIMUM_CONNECTIONS = -1 ; -1 allows unlimited connections.
$objWMIService = GetObject("winmgmts:{impersonationLevel=impersonate}!\\" + $ServerName + "\root\cimv2")
$objNewShare = $objWMIService.Get("Win32_Share")
$FileShare = $objNewShare.Create($SharePath,$ShareName,$FILE_SHARE,$MAXIMUM_CONNECTIONS,$Discription)

EndFunction