well unfortunately you don't have PicBasic PRO where everything is so much simple.

your example IF PORTA.0= will work in PBP.

Can you try this and post your results

Code:
     ' alias definition
     ' ================
     '
     Symbol  PORTA = 5
     Symbol  TRISA = $85                     
     Symbol  PORTB = 6
     Symbol  TRISB = $86

     ' I/O setting
     ' ==========
     '
     POKE TRISA=255 ' set input to all PORTA pins
     POKE TRISB=0   ' set output to all PORTB pins

     ' Main Loop
     ' =========
     '
START:
     PEEK PORTA,B0  ' read the whole PORTA and place result into B0
     IF B0.0=1 THEN ' read bit 0 of B0 wich is the PORTA status 
          '
          ' If PORTA.0 is 1 then place all PORTB pins to 1
          '
          POKE PORTB,255
          '
     ELSE
          '
          ' If PORTA.0 is 0 then place all PORTB pins to 0
          '
          POKE PORTB,0
          '
     ENDIF
     GOTO START