Snow_Dog wrote on Mar 30^th, 2012 at 11:25pm:

Easiest entry from the US side is thru Prairie Portage.  You will need an RABC as there is no Canadian Customs there.  If you can't or don't want to get an RABC then you can enter either thru Saganaga or else thru Crane Lake.....

SD offers several excellent route options but I will make one correction to the info he has provided. You do need a RABC to enter at Saganaga (Cache Bay).
The only practical southern entry that does not require an RABC is Crane Lake but then you must make a stop at customs on the way in.