You need to look at your data sheet for the 18F452 page 76 & 77 as they tell you what bits to be set for RB1 & RB2. INTCON2 bit 4 & 5 set the edge to trigger the interrupt. INTCON3 bits 6 & 7 set the interrupt priority, INTCON3 bits 3 & 4 set the enable mask and INTCON3 bits 0 & 1 are the interrupt flags set for the ports RB1 & RB2. It's all in the document.....