There are different possibilities.
Just try the different internet pages. They requirement is most of the times the same than for a "normal" airline. I'm working for one of these companies( but on commercial flights in a rebuild BBJ with only 44 seats on bord). You have to be very very flexibel, because most of the times you are on a kind of stand-by. There are flights planned already in advance, but very often also flights just coming up from one day to the other.
If you are flyingalone, you arealso very often responsible to order the catering acc. the wishes of the pax,plan the limo for the transport.....etc.
To manage a private life can be very hard.
Very good language skills and behaviour is a must and flexibility and abilitiy to work unplanned.
There are different airlines like
www.privatair.com Jet Aviation, Net Jets etc. Most of them make a first selection via the internet by offering a application form to fill out there.
Good luck.