Most any synth will do.
First, set the synth to mono mode (only 1 voice playable at a time). Then add 'glide' or portamento.
Put the filter's envelope attack at 0, decay at whatever, sustain at 100%, and some release time. Put a little attack time onto the amp envelope.
Depending on whether you want a smooth lead, or a biting one, set the cutoff low, or about midway respectivly. For the biting lead, add a little resonance (aka Q).
Try out different oscillator types. A sine works good for a smooth lead, where as you'll want a saw for a harder sounding lead.
That should be it for that kind of patch.
From there, experiment, and you'll learn much faster than someone explaining it.
-=bumpus=-