I was searching the archives here, and at EasyUO, for an easy and fast way to gain Parry. I couldn't find any scripts that did not take an incredible amount of set up. I heard that Sheep were a good way to gain Parry, but Sheep are not fast enough. The trick to gaining Parry is to have a creature hit you fast enough, so you have a greater chance of blocking their hit by Parrying.
At the most you'll be able to have nine creatures attacking you at once (eight surrounding you and one in the same tile as your character). Be sure to have a sustainable method of keeping your Hit Points above zero; bring hundreds of Bandages (and set a healing macro looped) or cast healing spells (remembering to prepare Protection first). Of course if you can find another player to stay with you for support, you'll find it far easier to stay alive (and sane). Or if you have Necromancy you can cast Horrific Beast and your heath will regenerate at 2hp/s.
What I did was walk around Haven with a self repairing shield (3+) and attack Hinds, until I had 8 attacking me. My healing macro was set and running. When I reached 80-85 parry, I switched to spellbinders (don't use Zombies, they are way too slow). After a couple of hours, I was at 120 Parry...!