Bitshares did it in an extremely poorly designed way by having an IPO where it's possible for the dev to to create thousands of mule accounts, send BTC in with all of them, get infinite premine + all his money back, then have plutocratic voting to determine delegates based on who owns the most coins afterwards.  The entire thing is a train wreck.  You can't get rid of mining for distribution, amongst numerous other changes they would have to do for how their system works to make it not a blatant scam.