Ok, so here's my own solution:
In your setup phase, you use the KC-Militia-Masq trick to pin your opponent, while setup your deck to have 3*Scheme, 2*GM, 2* Governor, 1 Militia, 1 Masqurade, and 6 KCs. Always top deck KC*3, Scheme*2, and 2*Governor. This should allow you to draw everything even when you are gaining a lot of Colonies.
After your opponent's deck has been wiped out, you first buy a Potion and 3 Ambassadors. In the next turn (you can no longer pin your opponent due to the potion) you buy a Possession, and Masquerade him a KC.
In the two turns your opponent can first buy a copper/curse; if he did it will be switched to a KC; then another copper/curse.
Note that I would let my opponent to play optimally after releasing the pin (so that in order to falter your plan, he will try to buy something); this is the more realistic situation where you can fight to win the pin, but the opponent can try to do something right after you release the pin.
Now we enter the scoring phase.
Start with the same KC*3 Scheme*2 Governor*1 to draw your deck. Play an Ambassador to give your opponent KC, GM, GM (return them all to the supply). Play the Possession thrice. Now play the Ambassador to give your opponent the last Ambassaor you have.
At this point, your opponent will have KC and a copper/curse in hand, and KC*1, GM*2, Ambassador*1 in the discard.
In his first possessed turn, pass. In the second possession turn, he must have a KC and a GM in hand. KC the GM to draw his deck. KC another GM; Ambassador the copper/curse to yourself; buy a Colony. In the third possessed turn, he now only has 5 cards in the deck. KC the Ambassador to return the 2 GMs and the other KC to your deck.
Now it's finally his own turn. Unfortunately, he has only KC and ambassador in hand! The best he can do is to give you back the KC and buy another copper/curse.
But now you know what to do. Just stuff him 2*KC 2*GM, and repeat the same trick. You can draw 27 cards from the Schemes and the Governors, with your starting 5 cards that is enough for the 8 Colonies and 8 Curses (if your opponent is doing his best to stop you!) which will appear in your deck near the end.
Is that what you think of as dominance? Wait a sec. There is still something better.
After you acquire a Colony, you can switch gears and ambassador him a KC and a Colony, using the 2 Ambassadors you have without KC them before you KC the second Governor. (start with KC-KC-KC-scheme-scheme-governor to draw everything at this point; play the last scheme and give up the last KC chance. Ambassador the two cards then KC-KC-Governor-Possession.) He will draw the two cards you gave him immediately by the second Governor.
In his possessed turns, he has a KC, a Colony, an Ambassador, and a copper/curse in hand. Now you can shorten his pain: KC-Ambassador the Colony 8 times in the 3 possessed turns, instead of torturing him with the same trick in 8 consecutive turns.