I think you have it a bit mixed up!

First, a voltage divider like that will not trigger IOC reliable or at all.

Second, in case of an interrupt what should the program do? You do not have an ISR to jump to.

Third, read the manual regarding the On Interrupt command to make a ISR subroutine.

The main idea is to make a digital input with preferably internal pull-up enabled. Then, an external trigger on that input will start PIC and jump to ISR.

In the ISR, you can recheck the input to make sure the trigger was real and then set the output for 4 sec. Then clear Interrupt flag, reset the output and go to sleep again.

Ioannis