Just to clarify on the above question. How do you specifically add your decoration to your own custom palette. When you add a *.ctl file without an actual control, LabVIEW doesn't know what to put down as all decorations are ignored when placing from the palette.
This has been brought up before (with a longer discussion here), but as of yet there hasn't been a mechanism for doing this. Maybe the next version of LabVIEW?