I can't tell you how to install it on the SCP Pack v1.6 made by ShivanSpS, however I can post step to step, and I believe it should work:
For Inferno:
1 - Download the Single File Version (INF_Main.vp) and the official SCP Patch update (INF_2Patch.vp), here is the URL:
http://inferno.hard-light.net/R1.htm2 - Once you extract (or install) all the content (I think it's in a EXE installer), Go to your Freespace2\ directory and there create a folder called "inferno" (without the quotes),
3 - Copy both files into the "inferno" directory (the filenames are "INF_Main.vp" and "INF_2Patch.vp")
4 - Go to the SCP Launcher and select the MOD Tab, there select the directory where you placed the Inferno campaing
(*) My update package has actually a problem with a Missing file, so I won't make this more complex, you can check it in my thread:
http://www.hard-light.net/forums/index.php/topic,37185.0.html-----------------------------------------
For S:AH is different, this will not work, because it's a Sub-Mod (**)
Sol : A History
1 - Download Sol: A History:
http://www.sectorgame.com/blaise/sah/Sol_A_History.zip2 - Unzip. Go to you Freespace2\ directory and there create a folder called S_AH or Sol_A_History (or whateaver you like)
3 - Copy the files there
4 - Download the fixed TBLs:
http://www.fileh.com/Shadow00000/Sol_A_History_FixedTBLs.rar5 - UnRAR and be sure to place them in your S_AH or Sol_A_History folder (ex: Freespace2\Sol_A_History\data\tables\ ), it need to be inside the tables\ folder, so be sure to check
6 - Go to the SCP Launcher and select the MOD Tab, there select the directory where you placed Sol: A History
(**) Forget about step 2, in order to work need to copy all the S_AH package + the Fixed TBLs in the "inferno" directory, however by doing this you will not be able to select the INF Campaing, because it will override all the data (the Tables/ *.TBLs), so I'll recommend you make a backup copy of it for faster replacement...(I have already fixed this in my update, but I still not finished it, so there aren't other choices)
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I know is somewhat annoying, I have already make a VP for S:AH so it's easier to install, however if you want to see what a messed package is you should try to play Solar Wars (probabily I can explain how to install it in 1 to 100 steps)