Lock/Protect Single Module

I have a workbook(1), contains a worksheet that once filled with user entered parameters, generates data through a VBA module (macro). This module(1) is a proprietary algorithm, and the author has locked the VBA project to protect the module from being tampered with/modified (and rightly so).

I take this data and use it as input in my own algorithms to generate more data. By locking "VBA project" in that workbook(1), I can't see anyway to add my own module(2) to that particular workbook(1). I can create another workbook(2), and write a module(2) there that reads the data from the first workbook(1), but then I'm left with TWO workbooks to do a single task, both have to be opened, and its just not a very elegant way of doing things.

I've contacted the author of the proprietary module(1), and he has no problem modifying the lock protection in the workbook(1) so that only his module(1) is locked, but VBA is not really his forte, and he doesn't know how to do it, or if it is even possible. I've checked many Excel Help facilities, and could not find an answer.

1. Is there any way to lock a SINGLE VBA module within a workbook?

2. Also, is there only ONE VBA project allowed per workbook? If I could add an unprotected VBA project, I could add my own module.

I may not be understanding the entire VB architecture properly, I'm using manuals from 1993, and On-line MS Help is not that "help"ful, so any assistance would be greatly appreciated. Mainly I just want to find out if this is possible or if its not, in which case I'll be forced to work around it in a inelegant fashion. It just seems logical that you should be able to lock just one module.