TC Helicon makes a couple of vocal processors that might work for you. I started watching them when I was in a band most of the members called "The DNA Band" -- Desperately Needs Autotune. Singer-songwriter BL thought he was God's gift to vocalization - he wasn't...I've found autotune works well on fretless bass with the right settings; ie. correction speed low otherwise slides sound fretted. It really helps with intonation - of course, I know learning to play fretless properly and accurately would negate the need for it but it's a good solution for now. I'm looking for a pedal that will achieve this for playing live - if anyone knows of one, please let me know.
BTW - Welcome to TalkBass.
(You may catch some heat for reviving a Zombie thread, but it's just the natural consequence of someone using the Search, like we also recommend, so rock on...)