Striker Kyle Lafferty and defender Chris Baird are suspended for the next World Cup qualifier against Russia next month and have not travelled here, giving the squad a more youthful look than usual.
O'Neill said: "We can only use six substitutions, and we only have 18 outfield players with us as well. We'll look at the scenario and see how the game develops but if there's an opportunity to get players game time we'll obviously take that."
He added: "The most important thing when you come into international football is that your confidence is high and you believe you can adapt and play at this level.
"It's always a psychological thing to go and play international football as well. Certainly those players are all in very good form for their clubs and they'll be keen to show they're capable of doing that at international level."
Lafferty's spot up front is likely to be particularly fiercely contested, with Billy McKay, Adam McGurk, Will Grigg and Josh Magennis all vying to stake a claim.
Inverness' McKay looks to be in pole position as the top scorer in the Scottish Premier League this season, while fellow uncapped players McGurk, goalkeeper Gerard Doherty and defender Alex Bruce will all hope to be given an opportunity at some point.
As well as being a chance to try out players ahead of the Russia game, O'Neill is also hoping Wednesday night's match will provide his first win as manager at the eighth attempt.
There have been decent results, notably a draw in Portugal in a World Cup qualifier, but there have also been draws against Luxembourg and Azerbaijan that have probably ended their hopes of reaching the finals in Brazil.
Captain Steven Davis insists progress has been made under the former Shamrock Rovers boss, saying: "There's a good feeling about the squad, everybody enjoys meeting up and everybody gets on well. It's nice to get a break away from your club as well. It's nice to see some younger players coming into the squad and getting their chance to stake a claim."
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- Kyle Lafferty