put a pin sized hole in them. or run the car and take the fuel pump fuse out. or, i dunno, can u really unpressurize the line without disconnecting from somewhere? i usually just popped the line off, but that was in my FB.

 

well i have a leak, so i guess there isnt much pressure there anyways

 

Rob Robinettes 3 gen RX-7 page has full instructions on how to de pressureise the system and them to preasureize it without over cranking the engine. Its under Engine how tos