Well, you can use iMacros to mass follow 1,000 people and hope they follow back. You can use the same script to unfollow them all whenever you want. I've been doing this for a couple of days now and I have 1.6k. Just note that it is risky doing this, there is a slight chance of getting suspended.
Mass Follow/unfollow code
VERSION BUILD=7601105 RECORDER=FX
TAB T=1
TAG POS={{!LOOP}} TYPE=BUTTON ATTR=TXT:Follow<SP>Following<SP>Unfollow<SP>Blocked<SP>Unblock<SP>Pen*