Ready to go . . . Taiwanese policemen take part in an anti-violence drill for the November elections. Taiwan's television viewers may soon find themselves watching commercials for political candidates. Under a proposal announced by the Central Election Commission, candidates will be allotted time on Taiwan's three TV channels, all of which are government-controlled. The change will mark another step forward for Taiwanese democracy, which began six years ago after nearly 40 years of virtual dictatorship.