I've heard some good MIDI renditions of steel before but none beats the real thing.
One thing is for certain, steel can be reproduced by MIDI much better than
a six string guitar. If you have a keyboard with MIDI control and a Pitch wheel
you can try to move the wheel to emulate a slide. There is a GM patch for steel
guitar. Once you have a sound you like, try recording it to your Cakewalk track.
You can then add effects. Incidentally, the sound you first hear may not
be axactly what you want but the effects (chorus/delay/reverb/compression)
may get it closer. Give it a few runs.......