Hanson has been edging ever closer to a return to action in recent weeks following a calf problem but City have been keen to show extra caution with the striker after an injury-hit start to the season.
The 28 year-old has been sidelined for the last five league and cup games after previously missing another five games towards the beginning of the campaign due to a similar calf issue.
With Hanson back in contention, McCall says City must now decide whether to take the striker with them to Oxford or keep him behind for further preparation ahead of next week's home double-header against Southend and Sheffield United.
Updating supporters on the striker's situation, McCall said: "James trained today (Thursday) fine.
"We now only really have James King and Macca (Tony McMahon) not training with us, although they are both running with the physios on the grass.
"We are getting back to that stage where we have a virtually fully fit squad to select from again.
"It is certainly far too early for James to come in and start but we are hoping he will still be in and around it.
"He trained well Monday and Tuesday with the physios and he has now got through training with us today as well."
Whether Hanson travels or not though, City will be able to welcome at least one player back into the squad after Josh Cullen returned to training this week following recent international duty with the Republic of Ireland U21s.
McCall added: "He played Friday night with Ireland, unfortunately they lost to a strong Serbia side, but it at least gave him an extra day's rest.
"It was good to see him get some more international experience under his belt, and he comes back into the reckoning for us at the weekend.
"He trains as he plays - it is always good to welcome a quality player back in the squad."