->  TW  But a NO pushbutton shoule be easily located. One could
->  TW> even use a Door Bell button.

-> not if you need to wire it to remove the battery jumper and place the
-> reset jumper when pressed

Then you need a "Double Throw" Pushbutton. A little less common but
should be easily obtainable.
A quick check of my Radio Shack Catalog finds that theri Cat #275-1549
will do the jobh.
It is described as a Mini SPDT(Single Pole/Double Throw) Momentary
switch. 
And cecking several MB booklets I see that typicaly there is three
pins involved and the Middle one is the common. Perfect situation for a
Momentary SPDT switch.
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