Dickov, who also worked under Grayson during a loan spell at Blackpool in 2008, trained with the Yorkshire side last week and will return for a second time later this week after a short spell on trial with MLS side Toronto FC in their training camp in Florida.
Grayson told the Yorkshire Evening Post: "We are trying to investigate a way round it. I won't say it will definitely happen but he looked fit and lively in training.
"Dickov has gone to America and he will have a look but he will be back with us on Wednesday or Thursday.
"We can then see where we are with FIFA and UEFA. He is a player I like. He has played for me before and I want competition for places."