Did you find and answer to this? If not this may help you, there are a few caveats though:
1) I don't write VB.Net/VBScript so this is a translation of C# Net to VB.
2) I'm not sure if VB.Net and VBScript actually are interchangable.
3) I would never use .Net for what your trying to do, I'd use python or something without all the .mess.
4) untested by me
Code:
Dim pd As New PrintDocument()
AddHandler pd.PrintPage, AddressOf pd_PrintPage
' Specify the printer to use.
pd.PrinterSettings.PrinterName = printer