Skyboy,
Ask everyone you come across from the time you check in to the time you are seated on the Aircraft. ASK ASK ASK until you get a yes and then stop asking. Keep your ID in your hand and flash it at every attempt to get a yes.
Your very very best bet is always the flight attendants on the aircraft. The purser if she/he likes you and there is room, will accomadate you if you are dressed nicely and they LIKE YOU.
Good luck but as someone said earlier, those frequent flyer miles are used by normal pax on those long international flights and chances of room in First or Business class are slim to NONE.
Remember to ASK ASK ASK.................
let us know how you make out with it.
HM