[VCDisAsm] is a command line program that can be used to 'disassemble' your
main.scm file, which contains all of GTA:VC's mission scripting, into several text files. You can then edit these text files with Notepad or whichever editor you like best, and reassemble them with
GTAMA to create a new
main.scm file.
The VCDisAsm.txt file details the command line arguments you can use with the program.