But how can the fact that you don't yet own a fretless make the fingerplaying harder? If you're not used to playing fretless it will probably be harder to play than a fretted. Maybe you just meant the sound, but since we're talking about finger-picking I assumed that was what you meant.
However you can get a jaco-sound without a fretted with some mid-range, a bit of treble and bass and stuff. And good fingerpicking, of course. (I'm a Swede, and I'm not that good at music sound-terms and effects in English, so if I just made a fool of myself it's because of that...)