Anyone with martial weapon proficiency can use a bastard sword two-handed. They can thus use a large bastard sword two-handed at a -2. If a character happens to have EWP:Bastard Sword, he can opt to use the bastard sword one-handed at no additional penalty. Meaning it's still a -2 for the size difference but he can use it two-handed or one-handed at his discretion. There is no rule for using a large one-handed weapon in two hands to negate the size penalty in 3.5.