Added these:

void Set(int i, dword bits, int count);
void Set64(int i, uint64 bits, int count);
void SetN(int i, int count, bool b = true);

Slight disadvantage is that while Set detects "aligned" operation (i % 32 == 0, count == 32), there is some penalty, but it seems to be quite small (about 3-4 opcodes). I guess if you want to be faster than that, you have to use Raw....