You can make the EP2 quad buffered but not EP8. There are 12 valid buffer configurations which are mentioned in the TRM(Chapter 1: EZ_USB Endpoint Buffers section)
To change the buffer configuration use the EPXCFG register.
For example, to make EP2-OUT Quad buffered you need to do the following:
Thank you hman! I resolved my question based on the TRM.