Yes, this is possible. You will need to create a random BIP39 seed and derive keys/addresses, and check if the address has the pattern you desire. Repeat the process until you find a seed that produces your vanity address.

Here's a solution using Node. Being javascript, this will run slowly, but it's what I know, and it will eventually get the job done. The script finds an address that has the search term either in all lowercase or all uppercase.

var bip39 = require( 'bip39' );
var bitcoin = require( 'bitcoinjs-lib' );

var searchTerm = 'newb';
var searchTermLower = searchTerm.toLowerCase();
var searchTermUpper = searchTerm.toUpperCase();

// Use a BIP44 derivation path for coin #2 (Litecoin)
var path = "m/44'/2'/0'/0/0";

var words, address, seed, root, i = 0;
do {
    // A value of 128 gives a 12-word phrase, and a value of
    // 256 gives a 24-word phrase
    words = bip39.generateMnemonic( 128 );
    seed = bip39.mnemonicToSeed( words ).toString( 'hex' );

    root = bitcoin.HDNode.fromSeedHex( seed );
    address = root.derivePath( path ).getAddress();

    if ( ++i % 100 === 0 ) console.log( 'Tried ' + i + ' seeds...' );

} while (
    address.indexOf( searchTermLower ) === -1 &&
    address.indexOf( searchTermUpper ) === -1
);

console.log( words + '\n' + address );