ASP.NET Download Limit Override in program

I have an ASP.NET page where I am using the ASP.NET Download control.  I am aware that .NET puts a limit of 4mb on the file and I can override that value either in the Web.config or Machine.config file.

What I would like to do is add a property in my settings for my application that my customers can control the size of the downloads individually.  I would like to read that property and then set the download size limit on the download page.

Reasons for doing this:

1) I can have different download limits in different parts of my application.
2) Client modifications to the Web.Config get over-written when they install a new version of my software.
3) Changing the machine.config now makes everything download at that limit and removes the flexibility to control file size.

So, I really need the ability to regulate the download size at the page level.  Does anyone know how I can do this?

Thanks,
Cory Jorgensen
Bitco Software