How to generate .bil tiles like in the pyramidal_tiff example

[Sgambe33]

Hello,
I noticed that the pyramidal tiff example makes use of preexisting .bil tiles rather than making a request to a server everytime. I was wondering how to obtain the same tiles but with a custom dataset. The application I am developing can't rely on a geoserver and should be usable offline. The dataset iTowns uses is this one.