Extended data security (xds) Dimension specific Access Permissions with out position or using user groups

I have seen various articles to filter dimension based on  positions assigned to a user and organizations hierarchy etc. This will use a temporary table My Departments populated from worker master and positions. With this logic If we want a dimension to be accessed by multiple users, we have to create that many positions in the system and attach to each employees. When we want to assign a user different dimension access either we create new position and add the user in this position or reuse any unused position if available. Moreover all users has to be attached to a worker and position. But in actual case all users may not be employees. Is there any way to configure Dimension access without positions in ax 2012. 

How Can we implement Usergroup wise dimension access in Ax?