I must admit I haven't begun to investigate the use of layers in MX just yet, but could you acheive this using Layout Mode or through the layer property inspector?
Alternatively, you might be able to locate one incidence of the code in Code View, copy it and do a Find & Replace, providing all your percentages are the same.
Failing that I'm afraid Anonymous may be right. Converting to tables is possibly the easiest way to do the task graphically as opposed to editing code.