I have seen it done with white lead paste, but I guess red lead would be just as good and probably cheaper.
The shipwright used a made-up gun, like a greaser, to force the paste into the void. It was very hard work.
The way I did it was to insert a wooden plug into the end of the tube with three inches protruding from the end, this is then sharpened to a point.
The red lead and putty mix is then forced into the hole bored for the tube, the tube is then pushed through with a bit of effort, the pointed wooden blank cutting through the mix and pushing it around the tube as it enters, extra mix added as necessary to fill any voids occuring....