How would you create a bassline like this in synfire?

Well, first thing you need to know is how to play this on a keyboard ;-) At least a few bars.

A guitar synth might be helpful to capture this kind of performance. And you need a synth/sampler that can reproduce this sound. 

Once you got a few bars of the rhythm captured in a DAW (probably best for recording and editing raw MIDI), Synfire can import it and create a number of Figures that you can use in any song and harmony.

(http://users.cognitone.com/tutorial/import)

This made me smile. He is using a guitar to play many different instruments, but I am always trying to play the piano to make it sound like a guitar! 

AAS plugins are awesome physical string simulation, great guitar and bass sounds

Hi Snares,

I have no standard workflow, it depends on what I'm doing. For the current song I'm working on I played a lead guitar solo part myself and recorded the audio, but I'm not great with lead guitar. So I recorded it into Synfire on a MIDI keyboard and for this particular song I'm using EWQL MOR 2 guitars (two guitars with one raised a third at a lower volume to give it more body). This works really well for this particular song. I had a basic harmony for the solo, but I then used the harmonizer in Synfire to get a much better chord progression for the solo.

Other times I've used a dry VST guitar and put an amp effect on it, but I've no particular favourite way of doing things, it's different each time.

For acoustic rhythm guitar, I sometimes play it myself and if not, I usually use Music Lab's RealGuitar.

I used the Core Bass Cherry by Orange Tree samples and played it into SFP with the Ableton Push using a drone. 

(https://www.reverbnation.com/groverbeatsxl/song/24925734-big-fern-risin…)