He basically accomplished the impossible, painting the DPJ (Democratic Party of Japan) as a party against change and the LDP as the party of reform,

He's accomplished the impossible, ... He's turned the DPJ ... into a party that's against change, and he's turned LDP, a party that's resisted (change), into the symbol of reform.

He wants to change the party so that it doesn't rely on the old factional political machines but becomes a more modern party that appeals based on policies,

Revolution is not a dinner party, not an essay, nor a painting, nor a piece of embroidery; it cannot be advanced softly, gradually, carefully, considerately, respectfully, politely, plainly and modestly.

It is a bit scary. It's like wondering who is going to come to the party.

A revolution is not a dinner party, or writing an essay, or painting a picture, or doing embroidery.