So you have users that have a read only/limited user access type. But you want to have them use CRM for Outlook to provide consistent user interface with your other users for consistency in your training and user documentation.
The problem, however, is that the configuration wizard for CRM for Outlook requires write access to CRM during the configuration, as it updates user settings during the configuration process. This means that if the user had a read only access mode, the configuration of CRM for Outlook will fail.
If you want to have users with read only access type use CRM for Outlook, you will need to give them read/write access mode during configuration, then you can change to read only/limited after the client is configured.