That may be difficult as an employee without your employer backing you up on necessity of employment expenses which are generally not written off (versus a contracted job which can bring a host of deductions). Read here: http://www.cra-arc.gc.ca/employmentexpenses/
and here: http://www.cra-arc.gc.ca/tx/ndvdls/t.../menu-eng.html
A contractor could pick a defensible home office deduction based on a pro-rated amount of the total annual cost of your residence and charge mileage, not expenses. Pretty limited unless it's your lifestyle (heavily focsed on clients and sales activities).
"I believe that banking institutions are more dangerous to our liberties than standing armies. If the American people ever allow private banks to control the issue of their currency, first by inflation, then by deflation, the banks and corporations that will grow up around the banks will deprive the people of all property until their children wake-up homeless on the continent their fathers conquered."
-Thomas Jefferson 1802