Short Answer: YES, its very possible. I installed new 555 Upper Ball joints.
Longer Answer: I just did this job yesterday with the pretty beefy ICON Ball joint Professional Set from HF. It came with all the correct cups and fittings to make it work...the threaded Rod piece definitely has to be facing downward, there obviously is no room whatsoever pointing upwards.
My truck is quite rust free (AZ) and I still had to hammer the actual Ballpoint out of the Knuckle Assembly with substantial force... then the Ball joint was pressed out of the UCA with the help of quite a bit of heat...took a while...these Yotas just LOVE to rust and seize components. So be ready for a fight...bring a lot of patience.
Once removed, make sure you thoroughly clean the mounting hole/mating surface, and apply some anti seize so the next time is hopefully a hair less painful. Pressing in was a breeze...just be aware its slightly angled not a straight press in. You need to use a slightly angled cup for that. On most Balljoints the boots will not be installed or at least not firmly, so you can take them off to ensure you don't damage them during install.
Good Luck!