Cummings - signed on transfer deadline day from Chelsea - will start at right-back in place of Liam Rosenior, who was allowed to join Ipswich on loan for the rest of the season.
Howard is in line to play in a three-man midfield after joining from Sheffield United while O'Dea - who made his Ireland debut against South Africa on Tuesday - could be on the bench as Rodgers sticks with former Doncaster man Matt Mills in defence.
James Harper joined Sheffield United on deadline day while captain Ivar Ingimarsson is close to a return.
Ingimarsson last played for the Royals in January but has recovered from his knee operation and has played two reserve games this week.
Chris Armstrong (knee) remains sidelined while winger Jobi McAnuff (back) is not fit enough to make his debut just yet.