Without getting into it about why I'm not a fan of 'emulation', which is essentially what you're asking for here, there are a few things you can do.nebulae wrote: (but let me put a limit on this by saying a preemptive fuck off to anyone who wants to provide the "hardware is better" argument...put that on another thread, byatch. *hugs*)
First off, if by 'warm' you mean analog feel, then start with the synth you're working with, if it's capable add a slight amount of detuning, do so. Secondly realize that from what I can tell modern soft synths are all generally bright as fuck, high end tweaking on the patches to give gloss. Gloss =\= warm, so apply the filters to roll off the overall high end.
Ohmicide is good for adding a tape feel, Camel Phat, even the free version can help.
I dunno I really just stick to colder synths soft wise, and use hardware for 'warm', so many reasons, but I understand the desire. Zebra can do some warm type patches, but wavetable synths, (which essentially all software and analog emulation synths are), just don't strike me as warm.