VB:如何为计算机的环境变量，增加一个系统变量，并赋值

Private Sub Form_Load()
Dim sysenv As Object
Set sysenv = CreateObject("WScript.Shell").Environment("system")
MsgBox sysenv("vbtest")
sysenv("vbtest") = "test ok"
MsgBox sysenv("vbtest")
End Sub