Yes it is possible to push hull resistance into the negatives. This works out to be a damage multiplier for damage that is inflicted to the target if resistance is driven negative. And the really nasty thing is that is multiplies ALL of the incoming damage, not just base damage.
"Beware the power of a full ranked and console backed Sensor Scan III"
My Sci runs a heavy 'damage through shields' set up with GWs, PSWs and all Disruptor Cannons/Turrets with SV. When I throw Sensor Scan on there (around 90ish debuff, IIRC) it'll eat you through full shields.