most forklift tech's use a forklift jack
(not a railroad jack) but a scissor type jack
Northern Tool
Global Industrial
Ebay
Grainger
The list goes on...

just google 'forklift jack' and there will be all sorts of hits.

Now just to clarify, this jack may not fit directly underneath the loadwheel outrigger arm so you would have to get underneath the side of the lift in another spot to raise that side of the lift to raise the outrigger arm enough to put a small chock block under it.
Once you have the wheels cleared from the floor they should be easy to remove.