Yovko,
if the users names and groups appear correctly in alfresco I don't think i know the answer to this one.
If i were you i would try the following.
if all of your users are in the same base DN, set your ldap.synchronisation.groupSearchBase=ou=people,dc=company,dc=com then create a group member by hand with the memberUID=username and see if it picks it up next time it syncs.
My gut tells me that what you want is not possible because the full DN is the only primary key of an LDAP server. For example, if you didnt use the full DN, alfresco would see both of the following users as the same person even though they are technically two different and unique enteries
uid=username,ou=people,dc=company,dc=com
uid=username,ou=orgUnit2,ou=people,dc=company,dc=com
My guess is the alfresco folk would stay with a primary key where ever possible.
Just in case i misunderstood what you want, this is the attribute associated with the username when a person imports it can be set to any ldap attribute you want that is in a user container. (eg sn,email,phone)
ldap.synchronisation.userIdAttributeName=UID
This attribute is an alias for the Full DN so, if your uid=yovko yovkov,ou=people,dc=company,dc=com
and that entry contained your surname as attribute 'sn' is value 'yovkov' (sn=yovkov)
you could set ldap.synchronisation.userIdAttributeName=sn and login using the username yokov
I have been having issues in alfresco labs 3 with ldap usernames. But, I am authenticating against an Active Directory server which stores the username as sAMAccountName. Basically the ldap.synchronisation.userIdAttributeName portion has not been working for me in labs 3 B and C