Nope, sorry. That will inevitably end up with you connecting the ground clip to mains neutral and causing a safety issue.
The other problem is that inserting a straight 1 - 10M resistor would form a low pass filter with the input capacitance of the scope probe, causing you to lose the high frequency noise that you're looking for.
The 'proper' way to do it would be use a high voltage differential probe, but you're looking at significant cost. However I think you could probably get away with a small (as low wattage as possible) toroidal mains transformer, say, 24V output. This would give you the important mains isolation that is needed.
One of the downsides of toroidal transformers, compared to ordinary ones is that they tend to couple more high frequency noise. This seems like exactly what you want.