"Michael is here given that we will probably make a decision in the next 24 hours on Pastie,'' Herbert said yesterday.
"We thought we would bring him here and, if we bring him into the group, then he's had a little time here and a feel for it.
"I don't know with Pastie. He's probably 50:50. That's why we didn't put Michael on the team sheet today [against the Solomon Islands]. It gives Pastie more time. He's up and about and in and around the environment but we need to be sure with him. He's being monitored and we will make a call on it tomorrow.
"Glen could have come on today - he probably wouldn't have done any kicking - but he will be in and around [the mix] for the semifinals and finals.''
O'Keefe is in the Olympic squad, has trained under Herbert at the Phoenix and been on scholarship in the US at Farifield University.
He joins a large number of the squad in Honiara who will also be in the Oly-Whites and the Nations Cup is proving excellent preparation for London.
In yesterday's match against the Solomon Islands, six players who are likely to be in the Olympic squad started and two others came on. Add in Ryan Nelsen, Shane Smeltz and Winston Reid, who are likely to be the three overage players allowed at the tournament, and the team is taking shape.
Neil Emblen and Ricki Herbert will also swap roles, with Emblen named as head coach, but Herbert's influence is bound to be strong.
"I think a lot of young ones will have a good idea of what international football is all about [now],'' Herbert said. "Coming to the islands is not easy.''