Basically no you can't, the S stands for Satellite, and the tuner, is only for satellite.
I seem to remember a DM 500c version, but as this is a satellite forum, and has nothing to do with cable, I shouldn't think you'll find much more information, on the forum.
I've read that the Satellite tuner, and canble, tuner, have different connections, so can't easily be switched, plus you would need to J Tag it, to alter the firmware.
Even when this was a reasonable receiver it didn't seem worth the effort, now it's so old it definitely isn't.
I have never owned any Dreambox, satellite, or cable, so can't confirm this information.
A couple of the VU+ models do have the option of fitting a terrestrial/cable tuner, but again is it worth it when, as Topper states, you can probably get a cheap cable set top box, for less than a VU+.