Yeah, you'd need a guitar synth. Even then, the programs I tried were only for really simple tabs. There was no way to indicate slides, pull-offs, hammer-ons, vibrato etc... and no way to indicate where you were playing on the fretboard.
You'd end up spending so much tweaking the tab that you might as well just do it from scratch to start with.
We use Guitar Pro to do our own here and it's pretty good. You have to manually enter the notes but it plays back a pretty accurate representation of you tab so you can edit it. Plus it does the regular score as well.