I've tried using the paint fur tool if that's what you're suggesting. Haven't had much luck with it; I haven't been able to achieve much control over it. It will paint in patches, and it's unclear how many clicks are needed to cover areas. It also won't reduce the baldness/desnity in some areas to completely 0. It will get close, but it's no 'smooth shave'.

Is there another way of going about doing that? Do you have a link to a tutorial?