"First and foremost, you hope that your star players are going to come through the Six Nations un-injured," said Irvine, who was Lions chairman when Britain and Ireland's elite travelled to South Africa four years ago.
"It's going to be a pretty demanding seven-week period, with very, very tough games. The game is obviously very physical now so we're keeping our fingers crossed that our big players are going to come through unscathed.
"You're also looking for your experienced players who you expect to be on the plane to maintain their form. Any successful Lions team from the past has had a hard core of players who have been there, seen it all and done it all before. You're looking for those guys to show their best form.
"You're also hoping that there will be a good few youngsters putting their hands up, showing that they are class players and are ready for the step up, because it is a step up - a Lions tour is a step up from the Six Nations. On most, if not all, past tours, there have been one or two youngsters who have gone out almost unknown and returned home real stars because they've managed to prove themselves at the very highest level.
"We're looking for those players and I'm pretty confident that there will be one or two who probably aren't household names now but might be in six or seven weeks' time."
The first weekend of Six Nations action features some huge individual battles as Wales host Ireland and Scotland travel to England and Irvine insists that the outcomes of those personal clashes are likely to have a major bearing on selection.
Gatland and his fellow coaches have said all along that they will pick on form rather than past fortunes and Irvine knows better than most that the northern hemisphere's premier competition will therefore take on extra meaning for every single Lions hopeful.
"Make no mistake, all these players know that they're very much in the shop window," added Irvine.
"There's going to be a huge amount of competition for places. I would suggest that the selection process will be done very much on form so there's every opportunity for those who play well in the Six Nations to book their ticket on that plane."
Irvine and Gatland will be travelling around Europe watching potential tourists in action over the coming weeks but it's not just from the stands that the selectors will be forming their opinions on who should be given the chance to face the Wallabies.
Gatland will be using every available tool to watch as much rugby as possible during the tournament, with Lions analyst Rhys Long and his team providing him with all the necessary information on who's been doing what across the four Home Unions.
"It's very important that we treat all the teams fairly so we've allocated which games we're going to and it's a complete cross section.
"Warren will also have the benefit of having Rhys Long and his analysts on board. It's not just a case of watching the games on a Saturday and Sunday. They'll be doing detailed analysis of all the games so, even if you're not present at a game, you'll still have a very good feel for who's played well and who's not played well.
"There's also a good cross section of coaches involved with the Lions in Graham Rowntree, Andy Farrell and Rob Howley who will be watching the games in a huge amount of detail for their countries. In that sense, I'm very pleased that they'll have all the players covered."