Welcome to Nikonians! As long as the sync voltage of your Metz flash is around 6V or so and the Speedlight is capable of non-TTL Auto flash mode and or Manual flash mode it should work well with your D5000 set in Manual (M) exposure mode using the Metz in Auto (non-TTL) mode or Manual mode.
I would think that since the E-500 is a digital body the sync voltage of the Metz Speedlight should be about 6V, though I would test it to be safe. In either case the Wein Safe Sync that George provided a link to would not hurt. Better Safe than Sorry! Good Luck and Enjoy your Nikons!