So if found this while i was browsing the Internet, hope this is not a repost:
It is possible for players who does not have enough rep/key to enter a Heroic instance to get in eventually:
1. Set the instance to Heroic mode
2. A player with rep/key enter the instance
3. Attack any creep inside, kill it or run out
4. Set the instance to Normal mode
5 .Everyone enter
This does not reset the instance. So, all creeps will be on Heroic difficulty, but will drop Heroic loot as well. Bosses will even drop Badge of Justic.
This has been tested extensively on Shadow Labyrinth and Mana Tombs.
I've not tried this because im at workif anyone can confirm i just wanted to contrib. this to u guys.