Go to the league page, then "My team" then "edit pre-rankings" then "edit my rankings" and on you "my rankings" list, put your round 1-5 picks IN ORDER as your top 5 choices.
If everyone does this, it will preserve our first 5 rounds of email draft. After that, you can just stop and let yahoo do the rest of the rankings (actually quite a clever system), or you can go hog-wild and make a huge list.
If you have a lot of time, you can put everyone elses picks in the 'do not draft' list, so its easier to determine who else to put in your list. Helio put the draft list in alphabetical order to help this out (switch to 'all' and rank by 'name' to find players quickly).
Something to note: Yahoo's rankings for DL and DB are GAWD AWEFUL! So at the very least, you may want to rank some DL and DB to avoid the 'add/drop' party that will happen after the draft.
Lastly, please tell me when you've setup your top 5 picks, so I can turn on the draft readiness (once you click 'ready to draft' it picks a time to draft, which is usually a couple days in the future, so its best to click it when you are bare-minimum ready, then setup the rest in the next couple days before the draft).