You actually don't need either of these things (and I don't know what you mean about objectives being "temporary").
I'm guessing that you're trying to do something like this:
(With different words, obviously.)
The scoreboard system supports colors for teams -- the syntax is /scoreboard teams option <team> color <value>
The sneaky trick is that you can make up fake players and add them to teams in order to color things. What I've done is made a scoreboard objective that displays as Date (/scoreboard objectives add date dummy Date) and then made three fake players (named Year, Week, and Day) join three different teams, to get them to show up in different colors.
Actually, I'm trying to color the actual objective. In this case, Date.
Turns out that's a heck of a lot easier. Open NBTExplorer, go to your map's name -> data -> scoreboard.dat -> objectives, and just edit the display name of the objective with whatever color formatting code you want.
You do not need to NBT edit as of 1.7. Just make a player (in this case Date) and a team (anything works), then /scoreboard teams join Date *teamname*. All that's left is /scoreboard teams option color *color*. That's it! Hope I got it all right!