Since some people either don't know or have forgotten.
Inferno SCP (or INFR2 as some of you call it) is a standalone mod using the Source Code Project. The mod includes all the required SCP media additions and fs2 retail files to run and does not require a copy of FS2 retail or FS2 SCP to run. The unpacked size is currently around 550mb and currently compresses to around 190mb for download.
How INF SCP is set up:
You'll create a directory such as x:\games\inferno and install all the files there. The core files of the mod are found in the data directory and NOT in VP files. Since the files are not in a single archive it makes it far easier for us to patch it and to add additions as new features become available. These files MUST NOT be edited as any edits will effect the main Inferno campaign and may break it. If you wish to make mods use the mod directory feature.
INF SCP can not be directly installed over any other version of FS2 as it will cause conflicts. Other FS2 mods or campaigns can not be used with INF SCP as most map names were changed to break compatibility with FS2 retail, because of this any FS2 ship using standard maps must be converted over to the Inferno map names before you can even attempt to load the model. FS2 retail can not be run on it as mostly only the interface art has been left unchanged, there is not enough left of FS2 to try to port it over.
INF SCP Modding:
All modding such be done via tbm files using mod directories. Using copies of the entire ships.tbl or weapons.tbl is NOT recommended as it will interfere with any future patches (R1 and Sol A History is an example) TBM files change only the required data and so will cause less conflicts and would be easier to update if any conflicts occur. I'll be going into more detail and producing a modding guide at a later date.
If you have any questions about this feel free to ask.