You would read the speed pot with analogRead(). The analogRead() function returns an int between 0 and 1023. To change that number to a range of speed values, use the map() function. If the range of values for speed are, say, 10 to 500 use:
int speed = map(potValue, 0, 1023, 10, 500);
Then, in the calls to the effect functions, use the speed variable in the parameter list.
CylonBounce(255, 0, 0, 0, 1, speed, 0);