By making an official application at a Mexican Consulate in Canada.
I know of no foreign born non-Latino that has acquired Mexican citizenship.
Maybe this person meant to say "resident status"? Not citizenship.
I am a Mexican citizen with a "green card." I know that virtually any foreigner can become a permanent resident in Mexico (I wish immigration laws were that easy in the US!) Citizenship, however, may be a little more complicated.
1st of all you'll need to complete residence in Mexico, This is done with an FM2. Every year you need it approved by Immigration for 5 years. On the 6th year your will receive your last stamp from Immigration Dept. which makes you and permanent resident. Then you may apply for ciitzenship with SRE (Secretary of Exterior Relations)in Mexico. Then you must wait 6-8 months while they review your case and decide if you will receive citizenship or not.