It indeed does not have a dipstick. Here is the filling procedure.
# Let vehicle idle for three to five minutes with accessories off.
# Apply brake
# Move shift lever through all gear ranges, pausing three seconds in each range.
# Place shift lever in Park. Important: Vehicle must be kept level on the hoist.
# Raise vehicle on hoist.
# Place oil container under fluid level screw.
# Remove the fluid level screw with the engine running at idle.
# Fluid level should be at the bottom of the fluid check hole. Because the transaxle operates correctly over a range of fluid levels, fluid may or may not drain out of the fluid check hole when the fluid level screw is removed. If fluid drains through the fluid check hole, this transaxle may have been overfilled. When fluid stops draining, the fluid level is correct and the fluid level screw may be installed. If fluid does not drain through the fluid check hole, the transaxle fluid level may be low. Proceed to ADDING TRANSAXLE FLUID.
# Install fluid level screw. Tighten 12 N.m (106 lb in)