?? Why would you not be able to use a shared function:
In class file 'DBFunction':
Shared
Function ReturnHello() As String
Return "Hellooooooo"
End Function
In asmx file:
<WebMethod(Description:="Say Hello", CacheDuration:=120)> _
Public Function SayHello() As String
Return DBFunction.ReturnHello
End Function
Works fine, unless i've misunderstood your question?