The only way I've figured out is to make the text in another drawing editor then save it as a block and import it into SolidWorks - but someone else may have a better answer.
You can blank out the value in the Dim, and then insert it as text. This would allow you to put the text and dim lines one separate layers.
By extension, you can double create each dim, delete the value in one dim. Put a text annotation in its place (as previously mentioned) and while editing that text, click on the second (duplicate) dim. After that, simply hide the duplicate dim. This will allow your dim values to automatically update.
