Creating a manager set and assigning permission to create accounts in FIM

Experts,

I want to give managers access to create account for new users in FIM Portal.
However manager should be able to select limited number of attributes during creation and update process.

Challenges:-
a - How to create a set of managers?
b - What type of MPRs should I create?

I tries with few MPRs but it works only when i select 'all attributes' when I just select few attributes it does not work and gives me the error
access denied.

Kindly suggest.

Thanks,
Mannn