If the security fuse has been blown, you will not be able to read the PLD in question ..
Reverse-engineering is possible, but it will likely require a logic analyzer and most definitely schematic diagrams of the circuit in question showing how the PLD you're trying to reverse-engineer works into the circuit ..
If the security fuse has NOT been blown, you can use any PLD programmer/reader to read the PLD in quesion and then disassemble obtained file with JED2EQN - disassembler ..
It is part of the OPAL package - o.zip, which can be downloaded from:
**broken link removed**
(see section: using PLD assembler) ..
Some additional info on this:
**broken link removed**
Regards,
IanP