Paste into selected cell

Ok,

1. click the legend cell you want to copy and copy it (ctrl-C, Edit - Copy, whatever works for you)
2. click the first cell you want to copy the format to
3. hold down the CTRL key and click the next cell you want to copy the format to
4. repeat step 3 until you have selected all cells
5. on the Edit menu select Paste Special and select Formats
6. Click OK

Now you have applied the format to several cells at once.

does that do it for you?