Keane is set to join the midlands club for a two-month spell until the Major Soccer League restarts in March.
He could face his Galaxy team-mate Landon Donovan in Saturday's home Premier League clash with Everton. Donovan has rejoined the Toffees for a second loan period.
Midfielder Bannan said: "Robbie is a player I watched when I was growing up. If you are getting players like that, it is good for the club.
"Robbie will add to the strength and the depth of the club as well.
"For the younger players, it is great to have a player of that calibre and experience in the squad even for a short spell.
"Our squad is pretty young experience-wise and having another wise head is only going to help us as a group.
"Robbie has been around for ages and played at the top level."
Keane's expected arrival is well timed with fellow striker Emile Heskey side-lined for up to a month with an achilles injury.