Well, how about this for a twist:
Use a mix of the Generic classes from Unearthed Arcana, along with the Racial Paragon classes as well.
I think characters like Etoh could be represented as members of the Spellcaster class that use divine magic. He didn't wear armor (IIRC), and only carried a mace (going along w/ the proficiency w/ 1 simple weapon for the Spellcaster class).
Slayn learned from books, but he didn't really seem to sit down & memorize/prepare spells from them. A Spellcaster that uses arcane magic would work for him.
Greevus could qualify as a multi-classed Warrior/Spellcaster (divine magic) & fit the bill of a more "standard" D&D cleric.
Deedlit could work as a Warrior/Spellcaster (divine magic), possibly with levels in the Elf Paragon class. Her spells would focus more on "shamanistic" spells.
Many of the fighters could be straight up Warriors, though with different feats and whatnot. Ghim possibly would have levels as a Dwarf Paragon. Out of all of the humans, the main character/hero Parn probably would be the only one with levels in Human Paragon (form the original series, at least).
Woodchuck would be a rogue/thief-oriented Expert.
Orson would be a Warrior, but burn many feats on Rage ability.
As for gear, I'd honestly say that a LOT of the fighters in Lodoss War used bastard swords, and not longswords--Parn, Ashram, Kashue, Beld, Fahn, etc. Ghim would wield a dwarven waraxe (perhaps even a slightly enchanted one). Deedlit would have either a rapier or an elven thinblade (exotic sword with rapier crit range & longsword damage)--a Finesseable weapon in any right. Slayn would have his staff, Woodchuck a short sword, and Etoh a mace (probably a light mace, from the looks of it). Orson had a greatsword, and Shiris had a Finesseable sword like Deedlit's.
I'd say Parn wore a breastplate, Deedlit some sort of light armor (like leather or studded leather), Woodchuck had leather, and the others didn't seem armored at all (Slayn without any armor, Ghim in regular clothes, and Etoh in his priest robes). Only Beld, Fahn, and Ashram seemed to be clad in some sort of full plate. Fighting with a shield only seemed to appear during practice/training fights (in the original, at least).
Well, that's my 2 cents on the matter.