you could also us NTC thermistors as a "soft-start" circuit, which will limit the inrush current, but rapidly decrease resistance within a few seconds. after the cap is charged, little or no current is flowing, so their resistance goes back to the high cold value. NTC (Negative Temperature Coefficient) thermistors are commonly used for inrush current limiting on switching power supplies that have a bridge rectifier and large capacitors as their input.
the other option would be to charge the cap using a constant current source using a transistor, a couple of diodes and a resistor. in this case the current would remain at a constant value that is preset, until the cap is fully charged. this actually charges the cap faster, since the charging current remains constant instead of exponentially decaying. this has the added advantage that the resistor required can be a relatively inexpensive 5 or 10 watt resistor. the transistor will need to be a power transistor with the voltage and current limits well beyond what the transistor will encounter in this application. since it is difficult to find transistors that can handle much more than 300V, you might be better off using a pair of cascaded transistors (not darlington, and not cascode) so that each transistor sees only 1/2 of the voltage. i've seen it done, but not in a current source, so give me a while to work it out on paper.
te reason the current setting resistor can be so small, even though the current being sourced is going through it, is that there's a constant voltage across it, usually 0.7V, but a zener reference can also be used for higher currents, but the voltage is still relatively low (a 12V zener could be used with a 1 ohm 15 watt resistor to set the source at 12 amps, but i doubt it needs to be set that high when 1 or 2 amps will most likely be plenty)