Sure - just pop out the cap and stick the driptip in. You can use anything handy to remove the cap: a pencil, biro, paperclip end.
Some people pull the driptip off to drip into the carto, some don't bother, they just drip down
through the tip. If you do that, then blow across it after, to shift any liquid stuck near the top.
Either way, angle it when dripping, so the liquid goes down the side and not into the centre of the carto.
You can get a lot in, depending on the situation - 10 drops at a time for example.