Illustrator is an excellent tool for putting text on a curve. Draw your curve with the Pen Tool, then switch to the Text tool and move the pointer over the line. Click when you see the cursor change, and you'll be typing on the line. You can change the curve after the fact using the Direct Selection tool, so you don't have to worry about drawing a perfect path on the first go. Then you can insert the text as a Smart Object in Photoshop, retaining the ability to change it later on, although switching out of PS to adjust a curve is a bit clumsy.