Are you on a ship ?

If this is to mainly keep the equipment from walking off (like a 3494 would)
I would just do the following...
Remember you have to be real careful not to screw up the alignment when you
attempt to "bolt it down"
I would pull a caster to get the bolt pattern for it on the atl frame...
then have plates made with the same bolt hole configuration but in this
plate have a big nut welded on in the center...
use this to somehow attach the atl to the floor...
        if raised floor have holes drilled through it and bring bolts up
from the bottom and into the nut.
If you are really on a ship where things are likely to be moving, weld some
plate down on the floor and use some form of small turnbuckle type device to
span between the floor and this bottom plate installed on the cabinet where
the casters used to  be.

You can't just anchor the leveling foot down because the ball will pull out
of the socket to easily on those...
but you might be able to design a more rigid foot piece that could be bolted
down and use the existing all-thread provided with the leveling feet (it
will unscrew out of the leveling foot)... but all that was designed to hold
the unit up off the floor, not down to it so stresses might play funny games
with it.

If you did some replacement of the casters it would have the least impact on
the environment (probably)

this is just an opinion

Dwight