I trust you know how to list missing libraries with the help of ldd (otherwise search here in the forum as there are several sample command snippets to be found).
Now how to identify candidate extensions for missing libraries: I'm usually a "CLI type of guy" but if you prefer 'appbrowser' then after connecting to the repository, click the 'Search' button once (so that it changes to 'Provides'), enter the "base" name of the library in question (e.g. 'libXss') and hit 'Enter'). On a TC 2.x system the result for this library should be:
Xlibs_support.tcz
Xorg-7.4-dev.tcz
Xorg-7.4.tcz
Thanks to my accumulated experience with TC I'm aware that the shared libraries are in Xlibs_support (they are also in Xorg-7.4, but I'm not inclined to install anything more then absolutely necessary).