1. Download and install Eclipse. I use $HOME/opt. For start it is enough the IDE.
1.1 I use the same folder for AOI and others + jre8 (for SH3D plugins compatibility).
2. Set an Eclipse workspace (I have ~8).
3. Follow Emmanuel's instructions to setup the workspace for sh3d plugins.
4. Start with a sample (VolumePlugin), make it work and then adapted it for others plugins.
When you decide to do this just ask for help (even in private to don't pollute the forum).
For me wasn't an easy task but now... it is equal difficult as at the begining.