Yes, Pixxi modules can be configured for use with a custom display. Please refer to the datasheet to find the currently supported LCD interface/protocol.
You will need to use Workshop4's Pixxi Configuration tool to setup the initialization code for your display. For instructions on how to do this, please refer to the manual available in Pixxi product page's download section.
If you're interested in using this processor with a custom display which requires a protocol/interface that is not currently supported, please submit a ticket to contact technical support team.
Note: When building the custom configuration, you might notice that the display draw a bit slower. This can be improved if the PmmC contains the required configuration rather than separate. In which case, you can contact our support team and send your working configuration for us to be able to build one for you.