vim'ing vba code, want auto-sync external code files with excel vba modules

[Paul]

I've used the VBE to write some VBA code modules, but when they get
large, I resort to vim and all the programming and unix tools that it
leverages. Basically, I copy all the code in each module to its own
file. But I have to be disciplined about keeping the external files
synchronized with the code in the VBE. When it comes time to test-run
modified code, it has to happen in the VBE, and any modifications
during troubleshooting must occur there.

To ease this dual-environment practice, is there a way for VBE to
update the code in its modules with text residing in external files?
Automated export from VBE modules into their respective files would
also be helpful. I am seeking a solution other than writing a VBA
program to do these things, because that would not be possible within
the current time frame (considering my limited experience with VBA).

I am using Excel 2007 in Windows 7 Enterprise 32-bit and Vim 7.3 for
Windows.