Creating "real" sounding instruments in SPLAT

Guitar is my main instrument and I usually end up in rock and metal projects. But I have a cheap keyboard that I write all kinds of genres on - classical, jazz, blues, etc - just everything.
I have SPLAT, which includes Rapture Session, Rapture 1.22, and Dimension Pro 1.5
On my cheap keyboard ($300 Yamaha), I would handwrite the scores in music then step write all the notes in the keyboard's memory.
So I purchased the Alesis V49 MIDI controller.
Is it possible to do that with Dimension Pro 1.5 and Rapture 1.22? Using the step sequencer? PRV?
I have a score that was written for cello, contrabass, violins, and piano - very dark sounding.
I have a score that was written for drums, guitar, sax, bass, trumpet and trombone.
Can you point me to some tutorials that will show me how to use SPLAT, Rapture, and Dimension Pro to step write the notes using my new Alesis MIDI controller?
Or does Dimension Pro and Rapture NOT have the "full" orchestra that I would need?

Thanks!

I find it easier to just play(record) the track capturing the midi and then quantize as needed to clean it up. I find this is usually faster and easier for me than using the step recording. With highly syncopated parts, like drums, step recording is best. You can then replace the synth or preset with whatever should be played. Or, if all else fails, you can copy the new midi track to a synth of your choice.
 
To each their own and YMMV.

I don't know about the second one but I would suggest using SI-Strings and TruePianos for the first piece rather than DimPro and Rapture.