To install it, you'd create a new directory in your FS2 folder and place all of ST:R's files in there.
Then you'd open mod.ini and add the Freespace 1 Port to the secondary mod list. Here's mine for an example:
modname = Silent Threat: Reborn v1.0;
image255x112 = fsport-str.bmp;
infotext = As the Great War rages on, you've been commissioned by Galactic Terran Intelligence for special intelligence operations. Your objectives are to contain the Shivan onslaught and preserve the fragile Terran-Vasudan alliance. But a series of suspicious events cloud the GTI's spotless record. Is the GTI setting you up or are the Shivans spreading their evil rage?;
website = http://fsport.hard-light.net/website/str/;
forum = http://www.hard-light.net/forums/index.php/board,140.0.html;
secondarylist = ,Freespace1port;
"Freespace1port" should be whatever your FS1 Port folder is named.
Then select in the launcher and all should be well.