<p>How can I add new application mapping in IIS using vbscript?</p>

<p>Thanks,</p>

Use a combination of ADSI with VBScript. There are several examples here:
http://www.microsoft.com/technet/prodtechnol/WindowsServer2003/library/IIS/4b976f46-3751-4f6b-ab68-5e19fa73a7b1.mspx