No, Tool Palettes can't handle overrides.
Looks like you'll need a file that contains a dimension style and a text style with the properties how you want it. Don't use object overrides, set the options in the dialog box. Then save that file somewhere accessible, so you can get at it with the Design Center, or with a button that uses the -insert command (like -insert;*SAMPLE;0,0;;;; -- didn't count the semi-colons -- the asterisk is so the block comes in exploded & doesn't leave its definition in the drawing).
Otherwise, leave a file open that has what you want, copy, paste, and match properties.
