Striker N'Guessan had a successful spell with the Addicks last season and has long been linked with a return to The Valley having failed to hold down a regular first-team spot at Millwall.
But finances dictate Powell will have to let players leave before bringing in any new faces after Swindon's bid to sign Bradley Wright-Phillips and Danny Green fell through on deadline day.
"Maybe one or two going out first might allow me to do something. But there's nothing imminent with regards to us bringing someone in," said Powell.
"A couple nearly went out last week, everyone knows what went on there and that's something Swindon have to deal with, and if it gets resurrected again, who knows?
"Everyone knows I like Dany, he did very well for us. He's been in and out of Millwall's squad. But at the moment nothing is happening there."