In order to make the 8 ohm 8" speaker into a Mid-Woofer and the 6.5" 4 ohm speaker into a Mid-Tweeter, you will need to use a crossover network to split the audio signal and send the appropriate frequencies to each speaker. The specific values for the crossover components will depend on the specific speakers and their characteristics. It is recommended to consult with a professional or do thorough research before attempting to modify your speakers.