HOW TO ALWAYS GET SUPPORT IN DRAFT (99% CHANCE)

I'm pretty sure they've actually given us actual statistics on the role selection outcomes, and it's not quite as bad as you're making out. Mid is probably the most desirable role (and hence hardest to get) and sup is probably the most in demand (and hence easiest to get), but they've tweaked the system somewhat since first release so getting your primary role is somewhat more likely.

Particularly given sup primary is only like 97% chance of getting primary role, other configurations are rather unlikely to be more likely to get support.

edit: Statistics regarding chance of getting whatever as your primary.

Or pick support as your primary.

I at times pick supp as my secondary and mid as my main and i get mid constantly so this doesn't always work.

Or you could put support primary and fill secondary.