How do airliners get from the factory to the client if the aircraft does not have the required range? Today I flew on an Embraer 190 of Kenya Airways. Checking in the tech specs this aircraft has a range of roughly 2900 km. Considering it is built in Brasil, I was wondering how do they deliver it to Africa since they would have to cross the Atlantic Ocean which I suppose is more than 2900 kms of range it has available.

Do they add temporary tanks and, of course, by flying the aircraft empty get more range out of it?
Sometimes they do add temporary tanks. Here's a picture of what Hawaiian Airlines had to do to get their fleet of 717's over the Pacific because they did not have the range.

I don't have the answer to your question specifically, but I would guess they either add temporary tanks and go from SBNT-GUCY which is not much further than max-range, or take the long haul through the US and Europe.

There's a Cranky Flier blog post about this.