Upfront I'm not familiar with Chrome or Chrome kiosk mode... However, if its the only instance you can try to look for it using WMI and then modify your Run command with additional arguments...
For more information on Run, see http://msdn.microsoft.com/en-us/library/d5fk67ky%28v=vs.84%29.aspx
Dim objShell, objWMIService, colItems
Set objShell = CreateObject("WScript.Shell")
Set objWMIService = GetObject("winmgmts:\\.\root\CIMV2")
Do
'Change Chrome.exe to whatever the executable is called
Set colItems = objWMIService.ExecQuery("SELECT * FROM Win32_Process WHERE Name ='Chrome.exe'")
If colItems.Count = 0 Then
objShell.Run "c:\scripts\kioskhomepage", 8, False
WScript.Sleep 5000
Else
WScript.Sleep 3000
End If
Loop