Create own instrument with articulation layers?

As I understand I can change the keyswitches for an instrument with instrument layers in Halion Sonic on the Edit-Layer Expression tab - but it is not possible to create your own instrument with instrument layer variations, right?
There are a few string instruments with key switches for legato / pizzicato / tremolo.
I would like to create instead now string instruments articulation variation key switches - legato / detache / staccato / spiccato etc.
If I’m right then to create my own instruments with key switching articulation layers with which alternative software can I create instruments for the Halion Sonic player?

Thanks, Thomas