This guide assumes you know a bit how WPE works.
1. Log in on main and alt (need high level, not sure how high)
2. Share a quest from alt to main
3. Search the ID (wowhead ftw) of the quest.
4. Turn ID to hex
5. Target the wow.exe youre accepting the quest on with WPE.
6. Open filter One, offsets 015 and 016 for the hex code.
7. Search quest ID of the quest you want and convert to hex.
8. Put it under the other hex.
9. Apply, tick filter and press "On"
10. Accept quest
Suggestions for quests:
Darkmoon fair Greatness decks, shadowmourne, legendary healing thingy from Ulduar etc etc.