Haven't gotten my hands on a Joye one yet but one of the reviewers said the condom method works on it.
October 4, 2010
Reviewer: Steven Cowell from Merriam, KS United States
It is a myth that these cartomizers can only be filled with a syringe and dismantling them. You can easily refill them with with the condom method. I put the threaded end into the tube. If it leaks out the mouthpiece end, I just wipe with a tissue.
There may be those who insist this is impossible, and I'm sorry I don't have the gear to make a video to demostrate, but there are others with YouTube vids online that show 510 cartomizers being refilled via the condom method, and I can attest this method works with the genuine Joye 510 cartos. I refill mine without a problem, as long as I don't overfill them and give them time to soak up.
You can also refill these cartomizers by just placing one drop at a time on the little hole in the metal tip of the carto. It will soak into the wicking about as fast as a small drip bottle will form another drop. About 15-20 drops will usually fill it, but you might get more or less, depending on how empty the carto is.