Ok, I'm on a new computer so my word processor of choice is down which makes me reluctant to do massive text-building, but let me see if I can give a better representations ofwhat I was thinking with a hacking feat line/class combo. My thinking is the GM determines when the hacking is possible, so the bonuses are big, but also situational. I'd also crib most of the earlier Spycraft rules for check times based on comparitive system grade.
Hacking bonuses are named bonuses that can be added to skill checks that involve making electronic/digital devices act in a fashion that is possible, but uninteded by the designer. Many uses of hacking relate to security with opening locks, deceiving cameras, and geting computers to volunteer what should be restricted files or access to their upper-level functions. The DCs for these checks are often substantially higher than normal checks to use these devices in the intended fashion and would be practically impossible without the hacking bonus.
New Gear Feats
Benefit: You gain a +2 hacking bonus. When you spend action dice to boost a check you are applying a hacking bonus to, the number of dice rolled is doubled.
Benefit: You may spend 2 action dice to boost rolls where you may apply your hacking bonus. At the begining of each session you gain four d6 action dice that may only be spent to boost or confirm criticals on checks where you may apply your hacking bonus.
Benefit: At the begining of each scene you gain two d10 action dice that may only be spent to boost or confirm criticals on checks where you may apply your hacking bonus.
I think the hacker archetype calls for either an Origin or a Bass class, but definitely NOT an expert class - fictional hackers don't grow into hacking from something else, it's what the bring to the story right at the outset. Using the feats above as a starting point, a base class might offer~
'Wired: At level 1, you gain the Haxor Basics feat.
Digital Rockstar: At levels 3, 7, 11, 15, and 19, your hacking bonus increases by +2.