I've been trying to do a LOTRO to D&D conversion. It's not perfect, but here are some rough guidelines.
Races: This part is the most straightforward. Hobbits, elves, dwarves, and humans correspond to their D&D counterparts. Treat High Elves and Stout-axes as elves and dwarves respectively. Beornings are the only instance of race as class.
Class: LOTRO Classes have abilities that correspond to more than one D&D class, so in most cases, there are different ways to do it.
Beorning: Barbarian (rage stat) or druid (shapechanging)
Captain: Paladin or cleric (they can buff other characters)
Champion: Fighter or barbarian (fervour is similar to rage)
Guardian: Fighter or paladin
Loremaster: Wizard or druid (animal companions, healing spells)
Minstrel: Bard or cleric (healing spells)
Runekeeper: Wizard or cleric
Warden: Fighter or ranger
A Brawler class is currently in development. Monk would probably be the best fit for this class.
Levels: Level 130 is maximum in LOTRO. I'm thinking about having every 10 LOTRO levels equal one D&D level. This would give a maximum D&D level of 13. If you like high-level play, divide by 5 instead. Round all fractions up.