McCoist completed his first signing as Gers boss on Wednesday after capturing Juan Manuel Ortiz and now wants to land the winger's fellow Spaniard.
Cuellar enjoyed one season at Rangers before leaving for Villa in 2008 and the two clubs have been holding talks regarding a deal.
However, Villa's £3million valuation of the versatile stopper is proving an issue and McCoist is not feeling confident about having Cuellar in his squad next season.
"I've made it clear that he's a player I would like to see back at Ibrox but he's under contract at Aston Villa and at this moment in time it looks like it might stay that way," McCoist told the club's official website.
"I think Carlos said some nice things about us to Juan which is obviously a help in terms of him signing. If he's as successful as Carlos and Nacho Novo then that would be great."
New signing Ortiz played alongside Cuellar at Osasuna earlier in his career and would be delighted if his former team-mate joined him at Ibrox.
Ortiz said: "Carlos is a good player and I know Rangers have been interested in signing him again so it would be good if that happened.
"I would be delighted about that. Apart from him being an ex-team-mate of mine, we are friends and he is an excellent player."