this won't work indeed... and you make it too complicated for what it need to be.

Code:
Start:
    for LOOP = 0 to 3
        PORTA.0[Loop] = 1  'High
        PAUSE 500
        PORTA.0[loop] = 0  'Low
    next
    goto start
END
MyPORT.0=PORTA.0 will work only once, If you want to alias a variable bit to a PORT bit... it's an all different story..