If you're not aiming for long-term retention, I bet you could memorize about 300 words in 3 days. With the GRE, the words are more predictable, and you can get good word lists. But, I don't know which 300 words you would study for the PCAT. You could go with the GRE words, but... you might get one of them if you're lucky. I bet you could boost your PCAT score by maybe 1% max. So, if you need that 1% go for it! Sounds like fun, cramming a bunch of words that you'll never remember later and probably wont be on the test anyway.
As an alternative, you might try some peyote, and see if magical coyote critters will travel through time and whisper the vocab answers into your ear. It might give about the same result.