Queue.cs

    public class Queue : DomainEntity
    {
        private readonly IList<User> _members = new List<User>();
        private readonly IList<User> _supervisors = new List<User>();

        public IEnumerable<User> GetMembers()
        {
            return _members.AsEnumerable();
        }

        public IEnumerable<User> GetSupervisors()
        {
            return _supervisors.AsEnumerable();
        }
    }

QueueMap.cs

    public class QueueMap : DomainMap<Queue>
    {
        public QueueMap()
        {
            HasManyToMany<User>(x => x.GetSupervisors())
                .WithTableName("QueueToSupervisorUser")
                .Access.AsCamelCaseField(Prefix.Underscore)
                .LazyLoad()
                .Inverse()
                .Cascade.All();

            HasManyToMany<User>(x => x.GetMembers())
                .WithTableName("QueueToUser")
                .Access.AsCamelCaseField(Prefix.Underscore)
                .LazyLoad()
                .Inverse()
                .Cascade.All();
        }
   }

User.cs

    public class User : DomainEntity
    {
        private readonly IList<Queue> _membershipQueues = new List<Queue>();
        private readonly IList<Queue> _supervisedQueues = new List<Queue>();

        public IEnumerable<Queue> GetMembershipQueues() { return _membershipQueues; }
        public IEnumerable<Queue> GetSupervisedQueues(){ return _supervisedQueues; }
    }

UserMap.cs

    public class UserMap : DomainMap<User>
    {
        public UserMap()
        {
            WithTable("Users");

            HasManyToMany<Queue>(x => x.GetSupervisedQueues())
                .WithTableName("QueueToSupervisorUser")
                .LazyLoad()
                .Access.AsCamelCaseField(Prefix.Underscore)
                .Cascade.All();

            HasManyToMany<Queue>(x => x.GetMembershipQueues())
                .WithTableName("QueueToUser")
                .LazyLoad()
                .Access.AsCamelCaseField(Prefix.Underscore)
                .Cascade.All();
        }
   }