It depends on what he wants when he says "monk" (which BTW has always been the problem with the DnD class, no two people can agree on what it should be).
Does he want Bruce Lee, destroying hordes of mooks with his fists? Then he should probalby stick with soldier or a soldier/barbarian multiclass, take all the unarmed combat feats plus the weapon focus/specialization/improved crit chain. This sort of "pugilist" would probably be the most appropriate for the Hyborian age.
Does he want Jackie Chan, bouncing all over the place like a rubber ball? Then I would suggest he multiclass with thief or pirate for the skill points (thief) and mobility (pirate). Actually, if you want to enable him you could let him take a special variant of the Pirate class - just change the "seamanship" ability so that instead of applying when the character is on board a ship it applies only when the character is wearing no armor and unarmed (but in any terrian, land/sea or whatever). That should make a prety good "monk"
Lastly does he wants Quai Shink Kain, the enegmatic kung-fu master? Then he needs to multiclass with Scholar and take the Oriental magic style. Choose either Divinations, Counterspells or Pretidigitation as a second style then cash in the rest of his styles and advance spells for bonus feats and skills. Use a staff (reach weapon) combined with unarmed strikes (5' reach) to effectively have both 5' and 10' reach and take the Meditation feats from Scrolls of Skelos.
Hope that helps.