"They've almost signed," Kapil, a board member of the Indian Cricket League (ICL), told Reuters.
"It is just a matter of legal papers. Other terms and conditions are agreed.
"Around 20-30 people are sitting and signing and going through the papers with their lawyers," he said.
"It is only a matter of time before we make announcements."
Warne and McGrath retired from international cricket earlier this year and the duo would be a huge draw after former West Indies skipper Brian Lara signed up this week.
Media has speculated that New Zealand skipper Stephen Fleming could also join, although organisers refused to confirm any names.
India's diversified Essel Group, controlling the nation's biggest listed media firm Zee Telefilms, announced the annual league in May.
They also plan to rope in some current India players as well as domestic cricketers with the inaugural event planned around October.
The Board of Control for Cricket in India (BCCI) has refused permission for ICL and asked Kapil, captain of the 1983 World Cup winning team, to choose between it and remaining as chairman of the National Cricket Academy (NCA).
Many of Kapil's former team mates have also signed up for the league which has Tony Greig and Dean Jones on its board.
Kapil said the idea was to spread the game and give players an opportunity to make a living.
"Everybody is interested in playing cricket," he said. "We just want to have more cricket and more jobs for people."
