If you've already seen an item in the game, you can search for it msglog.txt, which is in your character directory.

searching for the string salt:

(000000):c4h9:[2]{03880609} | 2 bags of salt

Then you take that code 0388 and 0609 and compare it to your current location. 0388 tells you how far east the item is and 0609 tells you how far south the item is (these coordinates here are in Driik).

The very last line of msglog.txt tells you where you are in right now:

(008000):r8hb:[=]{01F103A0} | Your character has been saved.

I am 01F1 east and 03A0 south, so I am northwest of this salt by a lot (in Sartola, to be exact). The numbers are in hexadecimal so: my current location is 1*256 + 15*16 + 1 east, and I want to get to 3*256 + 8*16 + 8 east, so I subtract my location from the destination and learn I need to go 407 steps east

And the south part, destination - location: (6*256 + 9) - (3*256 + 10*16) = 617 so i need to go 617 steps south.

So 407 steps southeast and 210 more steps south.

But it is more practical to do these exact calculations once you get closer to your destination, to go "i need to go somewhere in driik" and figure out where exactly in driik once you're already there.