Here's my technique in pictures. If there any critiques of how I could do it better please let me know.
Here's my stainless steel stock pot -

As you can see there really isn't much of lip to the pot. I found a stainless steel mixing bowl the exact diameter of the pot. It has a nice lip on it.

I use this handy little Black&Decker mixer to make the dough. About 1/2 cup flour to 1/4 water. I adjust the mixture with a little water or flour to make a dough that is sticky but not to sticky otherwise it just ends up in my hands.

I take the dough and break off little chunks and roll it between my fingers to make it about a diameter of a pencil and apply it to the bowl.

I do a bit at a time, overlapping the ends. I'll wet the dough a bit to make a good seal. Also, not seen in the pic is the dough wraps around the edge of the bowl.

Then I put the bowl on the pot and clamp it down with some black springy paper clips. I first clip 4 clips at 12, 3, 6 and 9 o'clock to make sure the bowl is exactly aligned.

Then I finish up by putting the rest of the clips around the bowl.

This method works really well. Takes very little time. I can fill up my pot with wash and turn on the stove. I have plenty of time to apply the flour dough, seal the bowl and assemble the rest of the still - which I can do in about 8-10 minutes.
That's all.
I've heard of the term flour paste as well. I'm assuming its flour and water but probably a thinner mixture for sealing up different applications like maybe pipe threads.