Is there a way I can iterate through the parameter that are sent to a function?

i.e.
private function somthing(ByVal This As String, ByVal That As String, ByVal Something As String)

End Function

Is there a way to access the values in This, That, and Something without using their name? say in a for loop?

Also, How do you do optional paramers in Visual Basic.Net

[Visual Basic] 
' The following example uses instances of classes in 
' the System.Reflection namespace to discover an event argument type.
Imports System
Imports System.Reflection
Imports Microsoft.VisualBasic

Public Class MainClass
    Delegate Sub MyDelegate(ByVal i As Integer)
    Public Event ev As MyDelegate
    Public Sub Fire(ByVal i As Integer)
        AddHandler ev, AddressOf Me.Fire
    End Sub 'Fire

    Public Shared Sub Main()
        Dim deleg As Type = GetType(MainClass).GetEvent("ev").EventHandlerType
        Dim invoke As MethodInfo = deleg.GetMethod("Invoke")
        Dim pars As ParameterInfo() = invoke.GetParameters()
        Dim p As ParameterInfo
        For Each p In pars
            ' YOUR CODE HERE
        Next p
    End Sub 'Main
End Class 'MainClass