Use NSIS to pilot Eclipse ?

Hi,

I'm installing Eclipse-based tools via NSIS, and I'd like to update these tools in the installer, by using Update Sites (Help > Software Updates > Find and Install > ... in Eclipse).

Is it possible to do that, and if it is, how ?

It's possible, but the installer has nothing to do with it. You have to setup the update site and then tell Eclipse about it using some extension point, iirc. The update site distributes only JAR files and not executables (at least the last time I used it).