Drive / Flight, arrange a chalet or somewhere to stay, buy ticket for Passportes. Job done.
In fact you done even need a ticket. The ticket gets you a welcome pack of gimmicks and promos, lift pass and entry to food stops with some basic packed lunch style grub, but you can just buy a lift pass and do the trails anyway. Plus you’ll likely be there for more than the day you buy so you’ll want a pass for other days. That said the Passportes ticket does give you a bonus lift pass for end of the weekend if you stay long enough.
Though having done the course in a day you need other things to do. You can either explore yourself, find the fun off piste or DH / bike part bits, or get some routes from a local or get a guide for stuff way off piste that’s more interesting. Possible a trip arranged through a company would be ideal for this, but you can get the info other ways.