There are a number of problems with his plan.
1. He can't change these things without a constitutional amendment
The Constitution Act 1982 §42 (1)(b) states:
(1) An amendment to the Constitution of Canada in relation to the following matters may be made only in accordance with subsection 38(1):
(b) the powers of the Senate and the method of selecting Senators;
This means that if Harper wants Senators to be elected or to have an 8 year term limit, he needs to get the approval of Parliament, the Senate, and at least 7 provincial legislatures who have a total of at least 50% of the population. The CPC has argued that the election part of this can be circumvented since, the PM will simply appoint whoever wins the elections. But lets not fool ourselves, even if I accept this method it's facially still a change to method of selecting Senators.