The tool is very easy to use. Simply take any .BIG archive, drag and drop it onto Gibbed.DeadRising2.Unpack.exe
A folder will be made coordinated to the archive you just extracted, edit the files you want in that folder, then take the folder, drag and drop it onto Gibbed.DeadRising2.Pack.exe
Once you do that, a black box will appear, this let's you know the tool is at work and is making a new .BIG Archive for the game to use, once the black box disappears, you know it's done packing. Take the file, and replace it with the original where you found it. Renaming may be necessary.