Also, if I can... can someone please explain how to do this ?
I'm pretty sure that you can do that using app tuckerbox...
See this thread: App Tuckerbox public release brings App Catalog feeds back to Preware | webOS Nation
And this one: App Tuckerbox - Your Apps On Your Devices
Hope this helps!
Indeed, you can do that with App Tuckerbox though not all of them will run right due to some missing features in WebView. But others do like the Facebook TP app for example.
App tuckerbox would be the answer if it was working. Something must be up with their server as it has not worked for me and some others for a couple of weeks. See the thread in the webosinternals section of the forum.