Idealistically, you should be making a DLL and set Com Visible on the functions you need to expose.
using System;
using System.Runtime.InteropServices;
namespace MyDLL
{
[ComVisible(true)]
public class Operations
{
[ComVisible(true)]
public int AddIntegers(int a, int b)
{
return a + b;
}
}
}
After you've compiled your DLL you need to register it with regasm.exe so that you can call it from VBScript:
Dim myObj
Set myObj = CreateObject("MyDLL.Operations")
Dim sum
sum = myObj.AddIntegers(3, 5)
This reply is based on the CodeProject posting How to call a .NET DLL from a VBScript by Raymund Macaalay. I recommend you read it.
Also, you should check other stackoverflow posting such as How to call C# DLL function from VBScript.