I've not tried them, but it sounds risky to me. Halogen bulbs get much hotter than ordinary bulbs (which is why they are made of quartz instead of ordinary glass, ordinary glass would melt); and both the windows in the gauges and the plastic housings for the warning lamps will melt.
Plus of course they draw more current, which will likely be a problem for the dimmer if you have one.
PS, Art, don't forget that the dimmer doesn't fit the same hole as the switch, nor does it fit well in the same location on the dash. The later panels have a larger hole in the center to accomodate the dimmer and the wiper switch was moved to the top.