I have a handy little gauge somewhere that sits on your panel and allows you to set your spoiler in percent deployment. I'll see if I can look it out and give you a reference.
EDIT: I found the gauge - it's called TAB_SPOILER.gau, although Google doesn't find it. Not surprising since it looks like it was a FS2000 gauge (written in 1999) although it works perfectly well in FS9. Shame, since all it is, is a small black box that sits on your panel with an 'arm' light for landing, plus mouse-activated variable percentage values for spoiler deployment in single digit increments, or in tens. I have no idea where I got it from!
