There actually was no need to seal either the vacuum hose or the plastic hose that goes into the dipstick. Just cut the holes in the top of the bucket slightly smaller than the diameter of both hoses, and press them in until they're snug. You can make a small collar on the vacuum hose out of duct tape if it makes you feel better - but it's not really necessary.

The key thing here is to have reinforcement in the bucket (I used a steel trash can). A 5 gallon plastic bucket, no matter how rigid it feels, will collapse under vacuum if your vacuum cleaner has sufficient power.

Troy K.
1995 E420