Did this by accident when leveling up a new char the other day..
Queue yourself up for the BG at that battlegrounds top level restriction when your that level. example 10-19 (queue yourself up at 19) — 20-29 (queue yourself up at 29) — 30-39 (queue yourself up at 39)
Now go finish your level.. so if you joined the 10-19.. level yourself up to 20.. and when you get in.. you'll be the level 20 in the 10-19 battlegrounds i think you guys get the point..
this only works once though.. if you try again it will put you in the proper level battlegrounds.. If all else fails I recommend The MMORPG Exchange for your WoW Gold needs. MMORPG-Exchange has supplied us for years and has great customer service and 24/7 instant delivery. Check them out! World of Warcraft Gold delivered instantly!