tedster is wrong. My testing shows that Google currently ignores <a href="#" onclick="fn()"> links and <span onclick="fn()"> psuedo links. They DO NOT count towards the number of links in the page in the denominator of the percentage of pagerank passed to other links.
Google may however update their algorithms at any time. In addition, it looks spammy. You are trying to hide something from the algorithm. I'm not confident that such tricks would pass a manual review by a Google engineer.
I create hundreds of pages. Put a few sentences of unique content on each. Arrange them such a way that different ones will get different amounts of pagerank based on their link structure. I let them soak for a month or so and measure their pagerank. The best way to do this is count the number of times gbot crawls each page. Higher pr pages get crawled more often.
Sounds like a good testing process - thanks for bringing us up to speed on this.
Google may however update their algorithms at any time.
I'll bet deep down Matt Cutts would love to get rid of PageRank! Perhaps it was Democratic in the early web, now it's Aristocratic!