First you will need to use Spectrum model security to configure user access to the models. Configure the model security so the "regular" users do not have read/write access to the models. Reference the "Model Security in OneClick" section of the Spectrum documentation.
Second, model the device with a read only community string
Third, populate the CommunityNameForSNMPSets attribute 0x11a7f with a read/write community string. This can be done by selecting the model and updating the attribute from the Attributes tab or using the Attribute Editor.
By populating the CommunityNameForSNMPSets attribute 0x11a7f with a read/write community string, users that have read/write access to the model through Spectrum model security string will cause Spectrum to use the community string from the CommunityNameForSNMPSets attribute 0x11a7f when they need to write to the device.