You want DF v0.43.04? Are you sure you don't mean v0.43.05? If you want DF v0.43.05, there are some Lazy Newb Packs that can make installing that easy:
BareBones Lazy Newb Pack for WindowsBareBone Lazy Newb Pack for MacIf you really want Phoebus for DF v0.43.04,
download Phoebus for DF v0.43.05 and then delete the /raw/objects/creature_next_underground.txt text file (to make it compatible with DF v0.43.04).
The installation procedure is different depending on if you are installing into an existing save or not. Installing into existing saves is more tricky and has more potential to mess things up. I'd recommend Lazy Newb Packs for installing and switching graphics. They make it so much more simple, less tedious, and less risky.
If you haven't created a save file yet:
Drag the files from /Phoebus/data/art/ into your /Dwarf Fortress/data/art/ folder.
Drag the files from /Phoebus/data/init/ into your /Dwarf Fortress/data/init/ folder.
Drag the files from /Phoebus/raw/objects/ into your /Dwarf Fortress/raw/objects/ folder. (Make sure you deleted the creature_next_underground.txt file from Phoebus first.)
Delete the /Dwarf Fortress/raw/graphics/ folder.
Drag the /Phoebus/raw/graphics/ folder into your /Dwarf Fortress/raw/ folder.
If you've created a save file already, after doing the above, open your /Dwarf Fortress/data/save/region x/raw/ folder, delete the "graphics" folder, then the /Phoebus/raw/graphics/ folder into there. Then copy the contents of /Phoebus/raw/objects/ into /Dwarf Fortress/data/save/region x/raw/objects/.