Invoke Code with External Library

I’m looking to write code in that I can invoke in UiPath using an Invoke Code activity. However, the program in question will be used to merge multiple pdf documents into one, and this seems to be either impossible or extremely difficult without using an external library such as Acrobat SDK. Is there any way that Invoke Code can be used with code that references/imports an outside library? Or must the code be completely raw, as if it were written in a shell environment?

Wondering if you ever found a resolution to this question? I am having a similar issue where I have functioning VB.Net code and would like to use it in an Invoke Code block as I do not see any of the drag-and-drop activities that have this functionality.