REMLAB requires an Apache web server (locally or remotely) with the ability to process PHP 4/5 scripts.
In the mid-nineties I attempted to develop my own Mech editor with Visual Basic after being inspired by the popular editors of the time. Around the time I started developing web sites, I realized that a HTML form based Mech editor could be possible.
In late 2005 I completed the first version of REMLAB. The interface was pretty clunky and slow, but it did everything intended. The following year, I competed an improved version that included an Ajax style interface which fixed most of the clunkiness and made the program behave more like a real desktop application.
The official source books that I used for reference were: The Compendium, Master Rules, Maximum Tech, Tactical Handbook, Solaris VII, BattleForce 2, and Total Warfare. As well as Battletech on Wikipedia, Battletech Wiki, and the official Battletech website.