There must be something in the air as when I spotted this thread some weeks back I was trying to recreate a Cosmosis bass, mainly for fun so I learnt a little about the old ways of bass whilst experimenting. 1) Try the Novation Bass Station VSTi, common bass synth of the era, I owned the original hardware back in the day. 2) Blend some square wave into your saw. I made commentary some time ago about an Etnica bass having some extra "vibrancy", adding some square in gets this result. You can also try adding a very very small amount of some kind of chorus type effect, 1-2pct (or maybe the very smallest touch of I.M. Wider, the trick with any artificial pseudo stereo is use a very small amount, be tasteful.) so you keep most of the low end stable but have just a very small amount of width to it, just enough to subtle-y tickle the ears. Just a very small amount and set it up on headphones and monitors for the right effect for both.
I imagine any soft synth you can blend some square and of course the obligatory envelope control LPF.
I have a love hate relationship with making old school inspired tracks. On one hand it can be fun, on the other it has all been done before and very, very well.
Tryptamine dream is one of my favourites from A.P. The main lead to me sounds like a Supersaw (with correct amount of detune/spread) in an arp/repetitive overlapping note MIDI pattern with some portamento/glide which gives it a slightly on the edge of being out of tune (which adds to its smeary slippery-ness) with a wash of very nice reverb. That should get you close.