I ran my heater hoses out of the engine bay, under the car along the fuel lines, then up through the shock inspection hole under the rear seat and through a existing hole into the trunk.

http://www.peachparts.com/shopforum/showthread.php?t=148416&highlight=drilling

__________________
1979 240D- 316K miles - VGT Turbo, Intercooler, Stick Shift, Many Other Mods - Daily Driver

1982 300SD - 232K miles - Wife's Daily Driver

1986 560SL - Wife's red speed machine