Try Tucker Gunleather in Houston. Not too many custom makers for the CS45, but he will make any of his leather (not his kydex designs) for it. I just ordered the "Texas Heritage" for my CS45. He has a number of styles, so you should be able to find one to suit you.
Tucker Gunleather
I have a Crossbreed Supertuck for a HK P7M13. It is very comfortable and I wouldn't hesitate to recommend it, but if I had found Tucker first, I would have ordered his "Answer" IWB model. I don't think either of them is availablefor the CS45 anyway.