I hope you guys don't mind i think i have .02 cents to toss in.
This is going to be a long one though.
Sup guys. Ok, I know what you are trying to do, and i can promise you it's possible to wheelie on the 250R, you just need to work on confidence... And technique. Ratty, don't know exactly how you are working on it, but i know 1st gear was mentioned? 2nd is more optimal, but i'll cover that later. What you have to remember is that you are on a 250cc bike. I myself have a 249cc dirt bike and i can promise you 1st gear is getting you nowhere without the proper skills and confidence to jerk the bike's handlebars in the necessary fashion to give you the lift that you need. Also, i used to be a semi-pro bmx-er when i lived in Texas (Not as glamorous as it sounds you really just get free gear if you wear it at an exhibition). Here is my thought, and you may wanna differ, you know, work around your own bike, but I personally started off with a bmx bike, and it teaches you the torque versus the actual pull or "Jerking" of your arms to begin the transition to one wheel. And the 1st gear comment earlier? Try it in second, the 250R is such a small bike that you have to remember to make the optimal power for doing a manuever such as a wheelie you are gonna need a little more speed and to be higher in the power band. The power band and the optimal speed for balancing a wheelie is around 12 to 25 mph and higher. 2nd will help you get that power at that speed. 1st can most definately be done, but it's easier to begin in 2nd to get used to it.
Overall Technique?
Part A.
Get a bmx bike, (cheap one for like $100 at wally-world(I know that's more money to spend, but it's better to teach yourself on something with no engine and 300 some-odd pounds less of damage inflicting force on your fragile body should you crash and burn) and learn to just control the basic 5 mile-per-hour pull up and relax while doing so. Go to a skatepark and get someone to teach you (Careful some people can be douchey) how to just jerk the bars and peddle in once and then once it's up try to spend as much time balanced on one wheel as you can get. I know it sounds stupid as all-he11 but hey at least if you bust your a$$ you only scrape yourself up not ruin a $4,000 dollar 360 pound machine. It's what i did. I learned on a $55 dollar Mongoose, then was GIVEN a Haro Bmx bike, and when i busted myself up too much to continue that sport (not from wheelies, from dropping into the bowl from 20 feet up Lolz) i just threw my honda Crf 250R into second and began revving and pulling on the handlebars till i could do circle wheelies. My suggestion at first would be until you are good with the wheelie, and since the 250R really won't overpower your weight, you should try putting your feet on the rear pegs. This suggestion does not cross over to when you manage to pull a 12 O'clock, because when you are that far back you will need the rear brake to bring you back to Mother Earth should something go wrong during this process. Sadly my dirtbike is at my dad's and it's sorta relagated to my little bro's playtoy now, but when i get back from Basic i am going to continue my one-wheeled antics.
Part B.
This is the daring part... once you have some seriously sick balance on the bmx bike try putting the left pedal back towards the back of the bike and with your left leg pulling up on the bike til the back wheel lifts. Depending on which leg you use you will notice that you can push the bike to the side also... Now if you get really daring and attempt this with the aid of the front brake and a certain measure (which is why i suggest wheelies first) of balance you may just be able to lean the bike forward into a stoppie and if so... It will be a proud moment for you, know that you have that sort of control over the bike. Its a bit different on the motorcycle, but as with the bmx bike it will require a bit of pull on the pegs and a bit of front brake. Note that unlike with the wheelie you will NOT put your feet on the back pegs. This will elongate your center of gravity and make the bike yet more unstable and yet more unpredictable.
Well thanks i guess for reading and if any of you do attempt any of this be sure to wear the PROPER SAFETY GEAR as well as take precautions and make sure you are in a CLOSED AREA. Not only is this stuff illegal (On the motorcycle not the bike Lol) but it can be very, VERY, dangerous. DO wear proper equipment. DON'T try any of this until you are ready and under safe conditions. This is why i would suggest the Bmx bike first it builds skills and confidence without much necessary room or much necessary money spent (new motorcycle are expensive!) and it's ALWAYS better to be safe than sorry.