How do we get this law in Colorado?

The only real issue I see here is the requirement to jump through different hoops to ensure you are "legal". With all of that, when SHTF will they have access to the records to prove that the firearms are, in fact, legal? Let's look at Katrina. Access to records of that sort woldn't have been available to anyone - local, state, or federal.

Are we to assume that the government will err on the side of the person in psssession of the firearm, or will they confiscate the weapon with a promise to return it if everything is found to be in order at a later time?

As others have stated, the 2nd Amendment is supposed to be enough to protect us from that very thing.

Colorado does not have any statutory provisions to stop the Governor from restricting/regulating the seizure of arms during an emergency. So it's up to interpretation -- which means, during an emergency, a Governor could do as he wants.

State Senator Scott Renfroe ran a bill in 2010 to change a portion of Colorado law regarding this. The bill died in the Senate Judiciary Committee, but here it is: http://www.rmgo.org/alerts/2010-billwatch.shtml

RMGO members were notified of it.

woe unto anyone from the california highway patrol or national guard that tries to disarm me during a crisis.