How hard can it be? It's mostly VB6 based so it's pretty simple. You'd just have to simulate the Excel calls and compile it as a VB6 program.
I agree in principle with people who say these should be proper programs or database-based apps rather than spreadsheets, but if you think it likely you've never worked in an office.
My last task at my previous job was using VBA code in Access to automatically reformat and import a billion and one Excel spreadsheets- then every subsequent one. Why couldn't the data be fed straight into Access, or the forms be changed to make it easier? "It's been like this for 15 years, why change it?".
Then more VBA was required to run the results of an Access query through a string of Excel spreadsheets (can't just incorporate the code into Access or change the Excel code to make it easier as "it's always been like this") before dumping the results using VBA into a template form in word (again, set in a decade's worth of stone) and telling Outlook to put it into a (standard) email. They select the form they want to process, click "process" and get presented with the finished form for checking- even the standard email's written for them.
A complete masterpiece of code if I'm honest- took bloody ages but it's all documented, commented, fault-tolerant and as efficient as it can be given what I had to work with. It took the whole process a minute to run rather than an hour manually typing and re-typing information- but I've been told it's now being ignored and they're doing it manually again because "it's always been done like that" and they "don't trust the computer to do it right" even though they get to verify the form as correct (haven't had any problems so far). Plus they cleared a lot of their departmental work backlog, meaning that there's less work- meaning there'll probably be layoffs as they just don't need as many people.
That's what you've got to compete with if you're proposing moving things to a proper system- decades of frozen-solid company dogma, people throwing ice over any unfreezing efforts to try and keep their technically unnecessary jobs, and Excel being "free" (it's always on their computers but this new technology means paying money. Why'd you do that when excel's free?).
Any man who can push through a full database and proper program based system for a well established company- and keep them using it- is truly either a man to be reckoned with.