Code:
PORTB=0
TRISB = 255 ' Disconnect all resistors from the circuit
' Some code here

DoItAgain:
          SELECT CASE XYZ
                    CASE ABC
                              TRISB.0 = 0 ' Connect PORTB.0 resistor to the circuit
                    CASE DEF
                              TRISB.0 = 0 ' Connect PORTB.0 resistor to the circuit
                              TRISB.1 = 0 ' Connect PORTB.1 resistor to the circuit
                    CASE GHI
                              TRISB.0 = 0 ' Connect PORTB.0 resistor to the circuit
                              TRISB.2 = 0 ' Connect PORTB.2 resistor to the circuit
                              TRISB.3 = 0 ' Connect PORTB.3 resistor to the circuit
                    END SELECT
                    PAUSE 500
                    TRISB = 255 ' Disconnect all resistors 
                    GOTO DoItAgain