Basically I used the info from
here dropped some items and scanned the memory for the item values to find the drop table's address.
But, this address was not the same every time I started pso(even switching chars changed it), so I had to find the location of a constant memory address that always pointed to where the drop table was.
Then I searched the memory for the address itself. And if it found nothing I subtracted a byte and tried till I did find it.
ex: I scan and find the first item on the floor is at memory address 0x5120. I scan the memory for 0x5120 and find nothing, so I scan 0x511F then 0x511E etcetc till eventually I find that 0x5110 is in memory address 0x1280.
So on startup of the addon I read from the memory address 0x1280 and then I add 0x10 (0x5120-5110) to it to get to where the drop table is.