O'Neill has a £25 million transfer kitty to dip into and the Birmingham Mail says he has not yet given up hope of persuading Chelsea to part with Cole.
"We have got just less than two weeks. I am hopeful we can sign some players,'' said O'Neill. "We are still actively trying to get some people in.
"I've the support of the chairman, who I think has shown his intentions and done exactly what he said he would in supporting the team.
"We might get another three players in and we might be stricken with the same situation as West Ham this time last year. We might not be able to cope but you've got a better chance if you've got the people in.
"I can get numbers in but I really want to try and get a bit of quality at the same time.
"I'm pretty pleased with what we've done, no-one has seen Cuellar play here other than his UEFA Cup run with Rangers, no-one really knows enough about what Sidwell could do. But it's great, it's competition for places which is exactly what I wanted."