A bass slide, other than upright or fretless, is very difficult to emulate, as the slide is not continuous but half-stepped as your finger slides over the frets.
Maybe an S900 guru can chime in... is there a bass slide sample in the S900?
If not, if you have a pencil tool and a good eye, you could draw in a fret glide by drawing in the semi-stepped (it's not REALLY exactly a half-step in the real world) slide rather than a straight line pitch bend (MIDI has pitch bend with it's own dedicated command, not any specific control #). But you also need to increase the default pitch bend range for the MIDI part - it's usually just a whole tone, you need at least a 4th and maybe a 5th of bend range (usually a MIDI commandable parameter). Then draw a descending ziggurat type pitch bend line and you are in the ballpark.
You might even get clever, and save a good one or two as MIDI files by themselves... just the commands for pitch bend range change and pitchbend data. Then paste into any style or SMF that needs one...
An arranger is just a tool. What matters is what you build with it..!