Level skip:
Make a backup copy of the file before proceeding. Use a text editor to edit the "preferences.dat" file in the "config" folder. Locate the following line:

const bool& ALLOW_LEVEL_SKIP =Bool(); // is FULLY_PROPER_BUILD no yes
and remove the "FULLY_PROPER_BUILD no" part so it reads:

const bool& ALLOW_LEVEL_SKIP =Bool(); // is yes
Press [F8] during game play to advance to the next level.

99 lives:
Make a backup copy of the file before proceeding. Use a text editor to edit the "preferences.dat" file in the "config" folder. Locate the following line and change the "3" to "99".

int& N_LIVES =Int(); // is 3

CPU control in story mode:
Make a backup copy of the file before proceeding. Use a text editor to edit the "preferences.dat" file in the "config" folder. Locate the following line and change the "no" to "yes".

bool& AI_TAKE_ME_OVER =Bool(); // is no

Disable CPU players:
Make a backup copy of the file before proceeding. Use a text editor to edit the "preferences.dat" file in the "config" folder. Locate the following line and change the "yes" to "no".

bool& ENABLE_AI =Bool(); // is yes