This section either needs rewriting or removal.
There are a huge number of ways to tweek MAKEMSI processing, I will never document most of these however you can generally work these out yourself, or ask. It will help if you have read the "Introduction to PPWIZARD" section.
I will add to this list below most tweeks that I use myself and any that I get asked for.
In the headers I provide many hooks for code insertion as well as for the overwriting of defaults. These may be "#ifdef" and "#ifndef" based but I am gradually migrating these to "#define?/#if" based as this is much easier to tweek from a user point of view.
If you see something like:
#define? FRED_SOME_VALUE TheValue
If you add (to a "YourName.mmh" BEFORE including "dept.mmh"):
#define FRED_SOME_VALUE TheValueIWant
Then you will have overriden the value. I do not recommend using a "#define?" command unless you can forsee the need for individual MSI scripts of yours overriding this value (better error validation).
This is demonstrated in the headers "DENNIS.MMH", "dept.mmh", "company.mmh" and other makemsi headers, each overriding some defaults at a lower level.
Note that you may sometimes wish (or need) to modify a value after including the header, use the "#define+" command for this.
These tweeks are much more likely to be modified in a future release than MAKEMSI commands, I do not promise to keep these even though they are documented. If something fails after an upgrade these are probably good first suspects.