DevExpress has the best support center I have ever seen, their Code Central really rocks and its fill with hundredths' of samples. One of them is is
eXpand has the above example as a module since its version 9 and you can use it by using the Xpand.ExpressApp.MemberLevelSecurity.dll assembly following the standard procedure for registering a xaf module.
But in v10 we have boost it a little bit and we have make it conditional so now you can apply multiple Member Access Permissions to a member
and by using the criteria member you can force the permission to be applied only to objects that fit those criteria