I'm sure you could generate frequencies down that low, any speaker will, weather or not it's a high enough power level to iritate a fly sitting on the speaker is another thing =) I've DC coupled to a speaker before and run it at 1hz, it's amusing if not completely useless.
What the poster wants to do with the speaker at this point is a big question, in a properly resonant cabinet even a bad speaker can generate decent power at a specific frequency, but it depends on the range he needs as well.