If you have the #56 switch controllers, Atlas includes then for use with their O gauge switches and twin coil switch machines. They are momentary, but not center-off, they are off as soon as the button is released no matter the position. They are wired as shown in the link posted above.
I have been using these for a few years now with my Atlas O 3 rail switches with no problems. However, I have no knowledge of the Lionel switches, what they are or how they operate? If they are twin coil like Atlas, I would think you should be fine using the #56 switch buttons with them.