For anyone else who might need to do this on their own project.
Registers:
/*signal A*/
LPC_SCT->OUT[x].SET = event_a;
LPC_SCT->OUT[x].CLR = event_b;
if you need to create a complementary signal A
LPC_SCT->OUT[x].SET = event_b;
LPC_SCT->OUT[x].CLR = event_a;
regards.