Don't Try This at Home, Kids

An article overview of the use of explosive charges for bonding high-voltage lines.

Northeast Utilities Strengthens its High Voltage Transmission Lines Using an Implosion Splice Method

The connector manufacturer's web site is:

http://www.implotech.ca/gallery.html

...and from that it appears that the people working on the hot lines have to bypass, then winch together, then cut the line in order to put on the sleeve.
(There seem to be separate sleeves - one for the steel wires at the center of the cable and another to go over the aluminum wires that make up the rest of the cable. It looks like they mechanically crimp on the inner steel sleeve, then slide over the outer aluminum sleeve with the explosive, then take cover and set off the whole thing.)