Ah okay, it seems to work:
(self is a reference to my custom scene)
self.test_RenderScript = gs.RenderScript(self.scene_path + "datas/test_RenderScript.lua")
The script just display a 2d texture at EndDrawFrame callback.
It works only when the script is initialized.
But the only way I can wait the initialization seems to be:
`while not self.test_RenderScript.IsInitialized(): pass
...But it don't work. Even after an Update().
How can I elegantly wait for my scipt initialization to give it my variables ?