See these forum threads :

http://chdk.setepontos.com/index.php/topic,2929.0.html  

http://chdk.setepontos.com/index.php/topic,2509.msg26731.html#msg26731

and this thread in the German CHDK forum  : 

http://forum.chdk-treff.de/viewtopic.php?f=7&t=2973   

(google chrome automatic translation recommended)

Orginal Incomplete Article  :

Setting up a development environment on your computer is necessary when working on larger Lua scripts due to the awkwardness of testing code on the camera. (remove SD card from camera, insert into computer, save file, remove SD card, insert into camera, run code. repeat repeat repeat.)

1) install lua - http://luabinaries.luaforge.net/download.html

2)