what is the voltage on the capacitor when you discharge it? if it's 100V, then to discharge the cap, you need to pick a resistance that gives a current within the capability of the resistor. so for a 100V starting voltage, and a 1 watt resistor (just for example) you would choose a resistance that would keep the heat dissipation below a watt. 1 watt would be 10mA at 100V, so you would want to use a 10k or larger resistance to keep the dissipation at or below 1 watt. the voltage across the resistor will only be 100V initially and will drop off at a rate determined by the time constant of the cap and the resistor. if you're using a 1/4W resistor, you want to increase the resistance proportionally, but be aware this also increases the time constant.
so the things you want to calculate are:
initial current through the resistor I=E/R
required wattage of the discharge resistor P=EI
if the wattage is higher than the wattage rating of available resistors, solve for the minimum R using R=E^2/P
the time constant is 0.67RC which brings you to 33% of the original voltage, so keep the resistor connected for at least 5 time constants.