I've found an article regarding the routing of an external clock for PSoC4. My team will be using the CY8C4247AZI-M485 in designing a custom board. We've found an article that gives a step by step process on how to add an external clock in the PSoC Creator (source link: http://www.cypress.com/knowledge-base-article/routing-external-clock-psoc-gpio-psoc-creator-kba90459 )
Based on the article, we can add an external clock using one pin set as input in the PSoC creator. However, our schematic design team reviewed how the CY8CKIT-044(dev kit for the CY8C4247AZI-M485) routed the external clock and it uses 2 pins.
Our team is still in the grey with proceeding with external clock routing. Hope someone could help us out.