This is one the hardest parts of the game. It combines blindly moving the cursor, screen scrolling, StopManip, skipping dialogs, and using items in the inventory. Here's one way to handle this part:

1. Walk to the glass o' water, press "U", click on the glass, click on the ocean (the ocean's hitbox is easy to miss, so be careful) and press both mouse buttons to use StopManip. Guybrush will fill the glass with sea water from a distance without picking it up.
2. Press "U" once again, click on the glass o' water, and click on the still.
3. Walk to the crowbar, pick it up, walk to the barrel, open the inventory, press the down arrow key and then Enter to select the crowbar, close the inventory, and click on the barrel. Alternatively, you can press "U", click on the crowbar without picking it up, and click on the barrel.
4. Skip the dialogue, click on the parrot (try to position the cursor on the lower part of the parrot, so the cursor is on the right item), open the inventory, press the down arrow key and Enter to select the cracker, and click on the parrot.
5. Press period to skip the dialog and click on the left so Guybrush starts walking. Then pick up the bottle and leave the beach.

Note that, in this video, I made a mistake and I positioned the cursor a bit too high when clicking on the parrot. So, after opening the inventory, the bottle of semi-grog briefly became the current item; I was aiming for the matches. I don't remember why things worked out in the end :D. Somehow, I correctly selected the cracker.