Awesome! But that has nothing to do with what he asked... You played as a LL team, you didn't sign a LL player to play in the Premiership like the OP asked.
I've signed a couple before, but never seriously. I did however try and play up Chris Herd at Aston Villa in FM2010 (he starts there, but he's in the reserves and about League 2 or Conference National quality...) and, whilst he did amazing in the reserves, all his games in the first team were horrible.