Ok, well I have some free time and I might as well try and solve the mighty problem of newcomers not knowing how to pack/unpack the misc.vpp_pc file, or any file of that type. *inhales*

The first thing you will want to do, if you haven't done so already is download the packing/unpacking tools. I'm linking to these rather than the WinRed tools, because I feel that they are more reliable at this stage. (No offense FeareD)

http://www.factionfiles.com/ff.php?action=file&id=364

Now you are ready to rock. Navigate to Program Files>Volition Inc>Red Faction Guerrilla>build>pc>cache. This is where all the important files are. If you are new, you probably want to start with a file called misc.vpp_pc, as this is where all the text-modified game information is stored, in the form of .xtbl files. You will find all the weapon properties in here (the fun part ^_^).

You want to extract Pack.rar and Unpack.rar to your desktop, or wherever. The location of these folders is important, you will need to remember where they are. Begin by copying the file you want to unpack to the Unpack folder, which contains Gibbed.Volition.Unpack.exe. Here it gets kind of confusing, so bear with me; Start up command prompt (either click Run then type cmd, or just click Command Prompt) and type in this:

[IMG]http://img515.imageshack.us/img515/3421/555-5555.jpg[/IMG]

DON'T type in exactly what I typed. You want to type cd, then the location of your Unpack folder, I just used my location as an example. Once you type that all in, press enter, and the directory will change. Then comes the actual unpacking. You want to type something like this:

[IMG]http://img96.imageshack.us/img96/744/555-5555.jpg[/IMG]

It's fairly straightforward, just type in the directory where you want the contents of misc.vpp_pc to go. Press enter, and it should show a long list of the files being unpacked. Wait a while for it to finish, when it's done the command prompt will go to a new line. You can go ahead and navigate to where you unpacked the files, and do whatever you want. (I'm not gonna explain how to edit weapons now, just packing/unpacking.) Once you are done, the process to pack the files into misc.vpp_pc is quite similar to unpacking. Just type this:

[IMG]http://img246.imageshack.us/img246/9013/555-5555.jpg[/IMG]
(Just like before, but to the directory of the Pack folder)

Then do this:

[IMG]http://img245.imageshack.us/img245/9870/555-5555.jpg[/IMG]

This will create a brand new misc.vpp_pc file in whatever folder you specified, with all the modded content that you added. Just make a backup of your original misc file, and plop the new misc file into your cache folder. You should now have a modded game :D (assuming you changed anything). Poast in here if you have problems.

Oh, and make sure you rename tables.vpp_pc to tables.vpp_pc.old or something like that, or else none of this will work.
-Alex