Native code programming technique in a vb6 class module

Question

I would like to implement this particular programming technique in my vb6 class, but I cannot understand how the "Nativecode" lines were obtained. Are these normal lines of code, obfuscated by some particular software? Is it possible to get the original code through reverse engineering? Could anyone tell me where I can find useful documentation about it? Thanks for any replies.

The code snippet comes from a series of classes, written in VB6, provided by the VBMapi program. These classes, inserted in a VB6 application designed for sending many emails, allow you to bypass the constant outlook warning messages.

In what way and with which compiler we get that native code to paste in a vb class and allocate directly in memory?