Packaging ioquake3 (NSIS)
To build the ioquake3 NSIS installer (on Windows or Linux) you need to first install 'make' (need mingw on Windows) and NSIS. On Debian and Ubuntu Linux, and most likely other Linux distributions, you can install the 'nsis' package.
After NSIS is installed you need to a few dlls that will be included in the installer, SDL.dll (v1.2.14), zlib1.dll, OpenAL32.dll, and libcurl-4.dll and place them in the ioquake3 misc/nsis/ directory. After you have the dlls change to the ioquake3 misc/nsis/ directory and run 'make'.
Quake III Arena
There is a NSIS installer for the Quake III Arena patch pk3s, which will also get baseq3 and missionpack pak0.pk3s from the CDs. You need to copy the patch data and id_patch_pk3s_Q3A_EULA.txt into the ioquake3 misc/nsis/ directory. After the patch data and EULA have been copied, run 'makensis ioquake3-q3a.nsi'.
One can package a mod for Windows using NSIS, so it can be easily installed, removed, etc et. Make a copy of ioquake3-q3ctc.nsi as ioquake3-yourmodname.nsi, modify it to suit the mod (change a few text strings, add the file names), copy the files for the mod into the ioquake3 misc/nsis/ directory, and run 'makensis ioquake3-yourmodname.nsi'.