First thing you need is a hacking program. I use Hex Workshop, but any one will work fine. But for these instructions, I'll assume you have Hex Workshop. Open your .zs* file in Hex Workshop, and you'll see columns of numbers in Hexadecimal format. The numbers on the left show about where you are at. Click on any offset. In the lower right, you should see something saying Offset: XXXXXXX, and the numbers it shows you are exactly where you are. Scroll down and find the locations of the offsets you'll need to change to edit what you want to edit.
If you don't know Hexadecimal, don't feel bad, most don't. It's a number system based on 16, unlike ours (decimal), which is based on 10. So Hexidecimal uses the letters A-F to fill in the missing parts. So after 9, it's A, then B, and so on. It gets confusing if you're not used to it... Luckily, included in Hex Workshop is a nifty calculator that can convert normal numbers into Hexidecimal and vice versa.
It can be confusing, but really it's not that hard to do. If you have any further questions, ask me. And if you're REALLY lucky, you might even get a response.
8034 - Boomerang (00 for no Boomerang, 01 for Wooden Boomerang and 02 for Magic Boomerang)
8035 - Number of Bombs in inventory.
8036 - Arrow (00 for no Arrows, 01 for Regular Arrows, 02 for Silver Arrows)
8037 - Candle (00 for no Candle, 01 for Blue Candle, 02 for Red Candle)
8038 - Ocarina (00 for no Ocarina, 01 for Ocarina)
8039 - Meat (00 for no Meat, 01 for Meat)
803A - Letter/Water of Life (00 for Letter/Nothing, 01 for Blue Water of Life, 02 for Red Water of Life)
803B - Wand (00 for no Wand, 01 for Wand)
803C - Raft (00 for no Raft, 01 for Raft)
803D - Book (00 for no Book, 01 for Book)
803E - Ring (00 for no Ring, 01 for Blue Ring, 02 for Red Ring)
803F - Ladder (00 for no Ladder, 01 for Ladder)
8041 - Power Bracelet (00 for no Bracelet, 01 for Bracelet)
8049-804A - Number of Rupees in inventory.
804C - Triforce Pieces (Each piece has a corresponding hex code (80 = #1, 40 = #2, 20 = #3, 10 = #4, 08 = #5, 04 = #6, 02 = #7, 01 =#8). Add the codes of the Pieces you want and put them in the offset)
804D - Sword (00 for no Sword, 01 for Wooden Sword, 02 for White Sword, 03 for Magic Sword)
804E - Shield (00 for Small Shield, 01 for Magic Shield)
804F - Bow (00 for no Bow, 01 for Bow)