The easiest way to get a copy of tklib is to pick up one of the Batteries Included distributions that include it, the most popular being ActiveTcl. You can also download the package directly from https://core.tcl.tk/tklib/wiki?name=Releases
Or, you can download a fossil snapshot of any tklib revision directly from the repository timeline , provided that you have logged in (anonymous login is sufficient). The login is required to prevent spiders and robots from overwhelming the site.
Or perhaps see if you can locate a tklib starkit .
After you have have the source, then use the appropriate command to extract the directory structure from the archive file.
At this point, the extension is treated similarly to any of the TEA script based extensions.
$ cd tklib-{directory}
$ ./configure --various --flags --as --appropriate
$ make all test install