Pot Chest Setup Steps

Enter GC from DMT or shop

Talk to Darunia's son to open the doors (if they're not already open)

Dump a fish (make sure you don't have hookshot in hand as you begin these next steps)

Before the fish disappears, drop a chu and pull hookshot

After the fish disappears but before the chu explodes, enter Darunia's room with hookshot in hand (waiting until the fish starts to flash to pull chu/hookshot is a decent cue)

Put away hookshot and exit Darunia's room

Break the 3 pots on the middle level (you can hookshot up there if you want, also their drops need to be gone by the time you enter Darunia's room again)

Superslide off the bottom left pot (it doesn't matter whether you break the pot to the right, but its drop cannot be allocated when you enter Darunia's room so not breaking it is probably safest)

Get an angle of 7E70 (1.2) / 75B4 (1.0).

Leave Darunia's room, drop the held item once both rooms are loaded and while you are at the above angle.

The pot chest is now set up.  In order to change item value you will need to pull out hookshot while 2 chus are loaded.  If the allocation is done correctly, the get item value will be determined by the byte at 801EC2F7 (1.2) / 801EBA37 (1.0) -- shooting the hookshot will change this value.  Setups for various items can be found here https://docs.google.com/spreadsheets/d/1gTyeY8ko0QEspd3wqL6czZVlpYjQ7Sr9KA9LIhbeIXw/edit?usp=sharing

----

There are two ways the steps above can be modified to skip waiting on the fish.  The steps leading into Darunia's room can be replaced with (note this setup can skip hookshot entirely, and is what All Dungeons uses)

Drop fish
Drop 2 chus
Catch fish
Drop 3rd chu
Drop fish
First 2 chus explode
Enter Darunia's room with fish and 3rd chu still loaded
Let final chu explode and exit Darunia's room
(the rest is the same from here)

With this setup, the pot chest's get item value will be at 801EC387 (1.2) / 801EBAC7 (1.0)

or alternatively if you have bombs (this is the setup 100% uses)

Drop bomb 1 (make sure hookshot is not in hand when you pull this bomb)
Drop fish
Drop bomb 2
Bomb 1 explodes
Enter Darunia's room with fish and bomb 2 still loaded
Let bomb 2 explode, leave Darunia's room
(the rest is the same from here)

With this setup, the pot chest's get item value will be at 801EC307 (1.2) / 801EBA47 (1.0)