Download of pksv_sourcecode1-2-1.zip (pksv_sourcecode1-2-1.zip ( external link: SF.net): 125,280 bytes) will begin shortly. If not so, click link on the left.
PKSV (Pokemon Script Viewer/Editor) is a small program written in C used to decompile, edit and compile scripts in Pokemon Advance ROMs. It has a GUI version (the one most of you will want) and the original command-line version.