There's no command line utility to do this (not sure why you thought that "translate psf" would do it. There's an old utility called "translate" which was for translating Edge databases into DFII, but that's nothing to do with waveform databases.
Spectre can write out SST2 directly - maybe you should have done that?
Also, ViVA (run "viva" from the command line) can iteractively export SST2 for selected signals in the results browser (this is in IC615). I don't think you can do this in wavescan in IC5141 though, for example. You didn't say which versions of the tools you're using.