Ospreys star Williams heads into next week's RBS 6 Nations clash against Ireland in Dublin within sight of a new national record.
He is just one try behind Wales' top marksman Gareth Thomas, who collected 40 tries in 100 Tests - almost twice the number of games it has taken Williams to reach 39.
Assistant coach Howley said: "Shane is a very talented, intelligent player.
"He believes he will beat players when he gets the ball, so what a commodity that is to have in your back-line.
"He is a very difficult person for defences to handle because he has quick feet and great balance, and everything he touches at the moment is turning to gold.
"Like the best strikers in soccer when they are around the six-yard box, Shane thinks he will score every time, so we are looking to get the ball in his hands as often as possible."
Williams is keen to deflect talk of record-breaking exploits while Wales focus on Ireland and then France in their quest for the Six Nations title and a possible Grand Slam.
But he is flattered to be mentioned in the same breath as national heroes like Thomas, Ieuan Evans, Gerald Davies and Gareth Edwards.
Williams said: "It would mean everything to break the record.
"Alfie (Thomas) is up there at the moment - he is a great friend of mine and one of the best - and to be able to say I have beaten the likes of people like Gareth Thomas, Ieuan Evans, Gerald Davies and Gareth Edwards is incredible.
"To have your name up there in the same sentence as those guys, anyway, is amazing.
"Looking back on the start of my career, I just wanted to play local rugby for Amman United and score tries as they came.
Eight years later, I am up there trying to score tries to be the highest try-scorer for Wales.
"Saying it now, I still can't believe it, to be honest. It doesn't sound right coming out of my mouth!"
For Williams though, who has never scored against Ireland or France, everything is about team success, rather than individual honours.
He added: "We are playing some good rugby and we are working opposition teams very hard for the full 80 minutes.
"With the players and coaches we've got, we should be aspiring to do well.
"We've lacked confidence before, and it has shown on the field, but it is funny what a victory can do.
"The self-belief is there again, and we are playing rugby that certainly suits the personnel we've got in the team.
"Yes, it would be great to score in the final two games - providing that means we win the Triple Crown and Grand Slam."