I think we can simplify that a bit:
 Code:
$IP=InputBox("Enter IP Address")
$=MessageBox("You entered: '"+$IP+"'","Result")

Function InputBox($sPrompt,Optional $sTitle,$sDefaultValue)
    Dim $sc, $result
    $sc = CreateObject("ScriptControl")
    $sc.Language = "vbscript"
    $result = $sc.Eval('Inputbox("' + $sPrompt + '","' + $sTitle + '","' + $sDefaultValue + '")')
    $sc = 0
    $InputBox = $result
EndFunction