Don't worry, it won't get into the reservoir, but will just fall down into the tank of the cart. Lift the label very carefully with a razor or an X-Acto knife and trim it away from the filling hole. Handle the bottles and the syringe very carefully. Load the syringe a little at a time to fill the cart's tank. Fill the tank slowly, being careful not to splash or overfill.
Last step is to thoroughly clean the syringe.
Our newly charged ink cart works well and actually seems to have a little more intensity than the standard Cannon carts. I cut back on the saturation in Photoshop and was able to print nice images at a much lower color setting. You'll want to do some testing. JR Inks has refill kits for all black and color Inkjet cartridges. Refilling takes only a few minutes, and one JR Inkjet kit will refill 3 to 6 cartridges.