This is the german manual off how to operate the 262. And in perticulair how to get out. No mention made of last part of the hood blowing off. I think it does but no proof yet.
According to an english translation of the Pilot's Operating Instructions, the rear section does jettison, under the section 'Bailing out':
"1. reduce speed. 2. Loosen the throat microphone. 3. Separate the helmet coupling. 4. Operate the canopy jettisoning handle. (The central and rear portions are jettisoned). 5. Climb out..."
The picture of the rear canopy in post #284 appears to confirm your suspicions; theres a spring mounted mechanism attached to the left hand inside rim, and the spring loaded point at number 29 looks to be the centre cross bar at the foremost lower edge of the rear canopy, which butts into the cable operated lever mechanism shown in the top image of the same post, that appears at the forward rim of the rear canopy. It looks like if you pull the cable operated lever to the right hand side of the centre canopy, the spring at No.30 extends downwards and thus the rear canopy shoots off. That's my interpretation of the diagrams anyway.
On further investigation by looking at photographs on a Me 262 cockpit interior, these confirm my theory. There is a red lever on the right hand side of the cockpit, with what looks like "Kabine-Notzug" written on it that is cable operated, as in the illustration, although the crank assembly at the centre of the rear canopy's forward edge shown in the top picture is hidden by a sill. The above mentioned spring mechanism is a red herring as it attaches to the top rear sill of the centre canopy and stops it from falling to the right when it's opened.