Step 1) Put the printer ink cartridge on some paper towels in an area where you can tolerate a spill.
Step 2) Look at the printer ink cartridge. This cartridge has two chambers. The Lower chamber is filled with a sponge. The Upper chamber is an empty ink reservoir.
Step 3) Put enough ink in the Lower chamber to saturate the sponge by injecting some ink through the ink exit hole on the bottom of the printer ink cartridge. Be sure that you do not push the sponge into the cartridge, or it will not make proper contact with the printhead when installed in the printer.
Step 4) Temporarily tape over the ink exit hole to keep the ink from dribbling out.
Step 5) Make a hole (by drilling or melting)into the Upper chamber. We suggest making the hole on the top of the printer ink cartridge.
Step 6) Inject ink into this new hole to fill the Upper chamber.
Step 7) Seal the new hole air tight using hot glue or black electrical tape. Do not use ordinary masking tape, duct tape, or scotch tape, since these will not make an air tight seal.
Step 8) Remove the temporary tape on the printer ink exit hole and insert in the printer.
Source: oddparts.com