Yep. Don't compress it.
If you're using a sequencer and your performance is iffy, record into a MIDI channel and then go in and edit the velocity or change the synth patch/program/preset in such a way that velocity doesn't affect the amplitude much.
I will however compress some subby basslines with something like an 1176LN for coloration/distortion purposes.
Furthermore... Before asking for 'guideline' settings, ask yourself why do you need to compress in the first place? What is it that you want to accomplish exactly?
Here are some questions off top of my head:
1. Want to even out dynamics (in which case, don't use compression, see first paragraph above).
2. Want to shape the attack portion of the sound.
2a. Do you want to round out the sound or make it more punchy?
3. Want to shape the release portion.
3a. Do you want to make it die down more quickly or "add" sustain or make the sound pump and breathe?
4. Want to make it duck/pump with the bass drum to pull it out of the way when the bass drum hits.
5. Coloration.
For points 2 and 3 again I'd work on the synth envelopes to get the sound "right" in the first place, and then maybe, just maybe finish off with a compressor.
In any case, all of the above point to different needs, which will mean settings that are different from one another.
Other things to note for synth bass:
1. Avoid using multiple oscillators. Single oscillators in bass, specially sub bass almost always work far better, with clear punchy results. If you want to have the sound of the detuned oscillators, then separate your bass into two halves: Mid-bass and subbass. Have your detuned oscillators occupy mid-bass and high-pass/band-pass those, and use a single oscillator with a clear wave (sine or low-pass filtered triangle for example) for the subbass. The reason for this is detuned oscillators "beat", in other words as the waves' cycles move in and out of sync with each other they will reinforce and cancel each other out, thus affecting the levels. In most cases these level fluctuations are quite big in the bass. The natural tendency is to strap on a compressor on these. But most compressors will do two things: suck out the bass frequencies from your bass and make the whole thing sound rather stiff and lifeless. By separating your bass into mid-bass and sub-bass you give yourself a nice solid foundation, and have the richness of the detuned oscillators w/o having to resort to less than ideal "solutions".
2. If you play two different notes at the same velocity but one sticks out like a sore thumb and the other is hardly audible, then your room acoustics are pretty screwed up. Don't try to fix this with a compressor or an EQ as there is usually nothing to "fix" on the recorded audio. What you need to fix is your monitoring environment. If it's impossible, then learn to identify your room problems and check your sound on a good pair of headphones.
3. I think I'll shuddup now. I could go on and on about stuff to try and do with synth bass. It's a whole world on it's own. Just ask any drum'n'bass nut