In a rare interview with World Soccer magazine to be published in Britain on Friday, Bosman, who now runs a T-shirt business and is a recovering alcoholic, says that the plan, strongly favoured by FIFA president Sepp Blatter, would be "a disaster" for football.
The Bosman Ruling, established by the European Court of Justice in 1995, barred transfer fees for players out of contract and removed the limit on the number of foreign players a club can field.
Blatter's 6+5 plan would curb the number of foreign players who can start a match to five. However, it faces a very tough path to ever be adopted in law.
Bosman, who says in the interview he is broke, but has not had a drink since December 2007, believes that if the quota system was approved it would create huge problems, especially for the Premier League, now the richest league in the world.
"The six plus five rule would create a big problem for every English club because salaries would sky-rocket again because English players would become much more expensive," Bosman says.
"On the other hand the foreigners are introuble and many of them will become superfluous. Standard Liege were able to balance their budget for the year by selling Belgium midfielder Marouane Fellaini to Everton for 18 million euros ($23.66 million)."
ENGLAND DISASTER
"They couldn't have done that without the Bosman ruling, they already have so many foreigners at Everton. He wouldn't have fitted into the (old) three plus two (foreigner) scheme.
"It would be a disaster in England, not just for the clubs, but for all the foreigners too. I'm warning the players now - we need to stand up against six plus five. Think hard. Players need to act and not always let themselves be pushed around.
"We're employees," Bosman adds. "UEFA and FIFA don't understand that and keep trying to circumvent that."
"We're workers, that's what the Bosman Ruling recognised. The governing bodies are trying to take back power. If we're not careful, it'll be even worse than in 1995 by 2010 (when six plus five is supposed to go into effect)" Bosman says.
Bosman, 44, admits in the interview to suffering from depression and recovering from alcoholism.
"People know there was a Bosman Ruling but they don't realise there's a guy who's given everything, who became an alcoholic,".
"I'm broke. I fought the good fight and I've paid the price. I just want to be recognised. I don't want to have lost 12 years of my life for everything to go back to the way it was."
