McCusker insists centre Davies has long had a substantial influence within the squad and he expects things to carry on as normal for both men this term.
"Hopefully it will work well. Two heads are better than one, as they say," said McCusker.
"Jon's had a lot of experience over the last couple of years of playing at a high level and we can definitely add something to the group by sharing the captaincy. I haven't got all the answers all the time so it will be good to have his input.
"He was definitely a leader last year. He's grown into that role in the last few years as he's grown in confidence with his performances for Wales. He's always there with suggestions and talking about the way forward so I don't expect that to change.
"I don't know exactly how it will work in games yet to be honest as we haven't got to that stage. I think it will be specified on the day who's captain for the match and we'll take it from there. Jon won't be here for every game with his international obligations but when he is here, he'll have an impact.
"Nothing will change for me personally. Jon had a big input into things last season and it will be good to continue that. And likewise, if Jon's in charge on the day, I'll just help out in whatever way I can and I'll just continue with my own role within the team."
The Scarlets finished fourth in the PRO12 last term, reaching their pre-season ambition of making it through to the knockout stages for the first time since the league adopted a play-off system in the 2009/10 campaign.
McCusker admits that beating bitter rivals the Ospreys to a semi-final spot felt like a job well done at the time but that the pain of defeat to Ulster in Belfast left them feeling that they could have achieved even more.
That hurt is destined to drive them onwards and upwards, with McCusker claiming that their recent experience at Ravenhill and their LV= Cup and Amlin Challenge Cup knockout losses at Northampton and Brive in 2012 will stand them in good stead this season.
"We got what we wanted last year but, looking back, it wasn't enough. We're looking to improve on last season, keep the consistency high and take that extra step into the PRO12 Final.
"Winning the big games is a combination of all three things (mental approach, experience and what happens on the day). We'll be more experienced for that loss to Ulster and the defeats to Northampton and Brive.
"We've taken a lot from those games, we've been there as a team now and hopefully we now know what it takes to win those kind of matches."