As President Clinton sang Al Gore’s praises yesterday to kick off the Democratic National Convention in Los Angeles, a few thousand protestors raised their voices outside the convention hall, many of them calling on Gore to divest his family of shares in Occidental Petroleum Corp. Environmental and human rights activists are criticizing L.A.-based Occidental for its plans to drill for oil on rainforest land claimed by the indigenous U’wa Indian tribe in Colombia. The activists have been dogging Gore to pressure the company to drop the drilling scheme or sell off his family’s Occidental stock. Gore and his representatives have had periodic, quiet meetings with enviros over the issue since February, but so far Gore has refused to take action or sell the shares, which are valued at between $500,000 and $1 million and are part of a trust for Gore’s mother, of which he is the executor.