i´ve found out that you can trade for 1st round picks quite easily.
(-simulate until the trade deadline)
-go to trade screen, watch those teams that have at least one free roster spot. those teams seem to be more likely to trade their draft picks for whatever reason.
-watch in which player the other team is interested and if you are willing to trade him propose trade. chances are good.
-if you trade with a team that has a very bad record you have good chances of getting high picks even if you won the championship
i tried it with the original rosters. used the knicks and traded mcdyess, houston, ward, k. thomas for 1st round draft choices, all in one season. i didn´t make the playoffs and got 5 1st round picks the next season, 3 of them within top 10.