The LSTSQ program described on this page about least squares fitting can be downloaded here. Right-click and "save as" to download a gzipped tar file of LSTSQ with Readme, source, Makefile, and binaries for Linux x86. If you want to compile from source, you will need to edit the makefile to point at your copies of PGPLOT and Numerical Recipes libraries.
You can also just download the Readme file.
bjw - at- astro.umd.eduUniversity of Maryland