The Tigers paid more than £1million to Peterborough for Mclean at the end of December, while Fryatt, who has scored twice in his first three games for the Tigers, joined from Leicester soon after in a deal that could rise to £1.6million.
Both players made their third appearance in Saturday's 2-0 home win over Barnsley and Mclean said: "It's going well. It will take a while for things to fully gel together, but we're working hard in training.
"We also worked hard on Saturday and we got the reward and the three points for that."
Hull have climbed up to 12th place after back-to-back league wins and remain six points adrift of the play-offs.
Mclean added: "To win at Portsmouth and follow it up with a win at home means we're on the right trail."