Won't work, I'm afraid. Anything from a non-
OGL source is a big no-no for LEW. Even
OGL material (ie, pretty much anything outside of
WOTC) is very rare, because it has to be accessible to the majority of players without us being jerks and reprinting the feats online.
What you CAN do is take those Libris Mortis feats as inspiration, and propose your own. Not a carbon copy, mind you, but something that fills the same function. Sometimes it works, sometimes it doesn't. Be prepared to argue your case, and good luck.
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Current Campaign: The Shattered Isles Homebrew - Hammer (Minotaur Fighter 8), Kirra (Drow Rogue 8), Shedin (Dragonborn Paladin 8), Zahar (Half-Eladrin/Half Drow Bard 8), and Seahorse (Halfling Rogue 8). Currently the group is in the Feywild, trying to discover who is poisoning the drow.
Check out my (non-gaming)
blog!