[Al Skierkiewicz]

Jose,
It is quite easy. Just wire two two pairs of two capacitors in parallel. The pairs then act as one single cap. Then it is a simple matter of switching one of the pairs to be in series with the other for normal operation and in parallel for charging. The second pole of the switch is used to switch the low side of the upper pair between the negative side of the charging circuit and the positive side of lower pair.
If you need a schematic, let me know.