I've never used a soft brayer to do it and find the regular rubber brayer easy to use. I just remember to 'anchor' the one end of the brayer in the middle of the CS. I then use really short back and forth actions with the brayer while I rotate the CS........kind of like the shaking you would have if you had suffered a stroke. I usually have to reink several times.
I also found that it was best to attach my CS to another piece of paper with removable tape. I found that if I touched the glossy paper that it sometimes left fingerprints.
Here is a card I did with this technique.
Gallery at Splitcoaststampers