Tusenfem:
By aquiring the charge (electrons, negative charge) from it's sorroundings in the "deep space". He (and other EC legends) fantasise that the stream of electrons from the galactic centre exists somewhere in the "deep space" (and those electrons are actually poring into the Suns poles, but it's another story,Electric Sun Urban Legend), whatever "deep space" means.
Presumably, it's the place around comets aphelion.
Putting some electrons in the positively charged nucleus will only produce a neutral nucleus, which in turn will unable the comet to interact with the Sun on next turn.
Putting some electrons in allready neutral comet nucleus (as a product of previous "discharge") is impossible, regardless of the speed of a comet.
Speed of the electrons expeled somehow from galactic nucleus, will be far greater then any objects in Solar system, because we know that the mass of an electron is negligable in the presence of the force that is 36 order of magnitude stronger then gravity
They will simply bounce of of the neutral comet nucleus, as åpointed by Tim Thompson in a reply from jun 2006.
But, somehow that is what JT concludes because:
and now comes the famous sentence (who said nonsence?:-)) from the same article cited above:
John Talbot

Quote:

Negative ions are difficult to produce by solar heating and are quickly destroyed by solar radiation

What?
Negative ions are difficult to produce by infrared radiation? No kidding.
That's no problem for Chuck Norris.