By bus you can reach Ribčev Laz or Stara Fužina, from there you continue the way by foot to the beginning of the footpath (about 5 minutes walk).
More info. about bus transportation: Bus timetables
The starting point to Peč starts at the Levov bridge in Stara Fužina at the cycling track crossroad. From there you just follow the sings for Peč and in 15 minutes you are a the top overlooking the beautiful lake.