I have removed just 2 keikies of the same plant a few months ago. A friend ask me to do that.
After the roots were long enough (around 5 cm, I cant think in inches..) we've cut not the keiki but the spike, leaving a few mm in the roots area. We used a very sharp knife and after the cutting we've put some cinnamon in the exposed part of the keiki and mother plant to prevent an infection.
The keikies were then put in a small transparent pot and filled with bark. I've tried to do this carefully not to breake any roots.
After 2 or 3 weeks one of the keiki produced a spike and then bloomed ...