Hi,
Your PSOC has an input clock.
All you need is a counter to generate an "enable" signal to control a toggle FF .... it's output is the SCL.
There is more than plenty of code in the internet on how to do this.
Also - I'm sure - there are complete I2C codes available.
*****
You have to consider if you want to implement "SCL stretching by an I2C slave".
This is a bit more complicated, because you need to take care about the true SCL state of the bus
..and you need to consider how to timeout this situation.
Klaus