Before I finalise the test phase. I had a few ideas I would like to include in the final project which make a lot of sense and provide much much more functionality.
1) The SK5126 chip provides 2 pinouts for a PS/2 mouse (1 clock, 1 data) which means that I can simultaneously, without changing the chip, have a small mouse/trackpad allowing for more precise control without having to reach up for the touchscreen. Blackberry's trackpads automatically spring to mind, but upon reading the pinouts online, I don't understand how I can interface this as PS/2 data. If anyone has any information or ideas on how to achieve this, please let me know.
2) As the keyboard occupies the only USB port on the entire phone, I am also thinking of adding a USB hub chip with power support. This will allow me to charge the phone and plug in all sorts of OTG devices without having to unplug the keyboard every time. I think this is relatively easy to achieve and there are many chips out there which facilitate this.
Let me know if you have any other relevant ideas I might try to incorporate into this project.