custom made idea:

do you know these kind of push-buttons used in arcade games? they are big and resistant, can't you mount a second push button under the axis from the first buuton?

the user press it (they have a tactile feed-back that make you sure that you pressed them...), if stills pushing the bottom of the axis push a second button...

like this:

(=====)
H
H
-------- level of first switch closed
(===)
H

second switch pressed if first switch squeezed further :-)

not elegant, but it's cheap and works for a prototype...

hth

orlando