Freeform dungeons allow you to place doors anywhere along the walls of dungeons and not just the centers. The following is from idontknow's tutorial.
1. To enable freeform dungeons, go to Quest, Rules. Then flip to page 2. Check the second rule, Freeform Dungeons.
2. Note that checking this rule removes an invisible border around the perimeter of the screen in dungeon dmaps allowing you to travel from room to room from anywhere on the edge of the screen (not just from the center).
3. However, in freeform dungeons, you will need to have 'overhead' combos for each part of the doorways you want Link to appear to walk under. Make these by right clicking on empty combos, selecting the doorway tiles, and then selecting the "overhead" combo type.
4. Place these on the edge of the screen where you want the center of the doorway to be.
5. Place the rest of the doors as you please. Note that they no longer have to be in the center of the screen for Link to walk from screen to screen appropriately.
6. Note that in freeform Dungeons, Link will still automatically walk 2 tiles out from the edge of the screen upon entering a screen; this is so that Link does not get stuck in shutter type doors.
7. You can use lock block & lock block 2 combos to make locked doors wherever you want now, instead of just in the middle of the screen.
8. Use the autodoor combos by going to Tools, Doors, if you still want to have doors automatically appear in the center of the edges of the screen.
9. Note that enemies will still not walk in open spaces that are on the outer combos of the edges of the screen, as if the barrier was still there. Also, enemy fire & Link's weapons stop at one tile out from the screen as well.
10. Keep in mind that all other properties of dungeons apply.