As well as the inclusions of Kelliher and McSharry, the other changes see both centres from the Wales game, Diarmaid McCarthy and Michael Allen, move out to the right and left wings respectively in place of Craig O'Hanlon and Mark Atkinson. Noel Reid will start again at full-back having recovered from a shoulder injury.
The Ireland pack have also seen some changes to the front five, with Brian Cagney coming in at loosehead prop in place of Denis Buckley and Patrick Butler is promoted to start in the second row instead of Brian Hayes.
The changes are part of a rotational policy as all players will play under the Festival rules.
Commenting on the game and the team selection, Ireland coach Peter Melia said: "We wanted to move things around in terms of selection and give some experience to some of the other players. We felt that Diarmaid (McCarthy) and Michael (Allen) are a really strong running threat and that they might be able to find more opportunities from the wings.
"This allowed us to give Michael Kelliher and David McSharry an opportunity in what I think is a strong partnership in the centre.
"We are expecting another hard game in the forwards again as Scotland really put the French under pressure in that area.
"We have made two changes to the front five as both Brian (Cagney) and Patrick (Butler) performed well when they came on against Wales and so have been given a further chance to shine."
Melia feels that Scotland will be another big challenge for his side, adding: "Scotland had a very good win against France, so they should come into the game with plenty of confidence. They have some powerful forwards and some real threats in the back-line.
"We were disappointed to open the Festival with a loss in front of such great support, so hopefully we will have another big crowd to support the squad tomorrow."
Admission to all the matches is free and information on fixtures, results, teams and other news from the Festival is available on www.IrishRugby.ie/U18Festival.
IRELAND UNDER-18 SCHOOLS TEAM & REPLACEMENTS (v Scotland U-18, 2008 U-18 Six Nations Festival, Saturday, March 29, Musgrave Park, kick-off 2.30pm):
15 - Noel Reid (St. Michael's College)
14 - Diarmaid McCarthy (Castletroy Community College)
13 - Michael Kelliher (St. Munchin's College)
12 - David McSharry (Templeogue College)
11 - Michael Allen (Methodist College Belfast)
10 - Luke Marshall (Ballymena Academy)
9 - David O'Driscoll (Presentation Brothers College Cork)
1 - Brian Cagney (Presentation Brothers College Cork)
2 - Niall Annett (Methodist College Belfast)
3 - Jack O'Connell (Clongowes Wood College)
4 - Patrick Butler (Rockwell College)
5 - Ben Marshall (St. Andrew's College)
6 - Dominic Ryan (Gonzaga College)
7 - Brian O'Hara (Presentation Brothers College Cork) (capt)
8 - David O'Callaghan (Midleton College)
16 - Risteard Byrne (Terenure College)
17 - Denis Buckley (Blackrock College)
18 - Martin Moore (Castleknock College)
19 - Brian Hayes (Christian Brothers College Cork)
20 - Mark Atkinson (Grosvenor Grammar School)
21 - Richard Bent (St. Mary's College)
22 - Craig O'Hanlon (St. Munchin's College)
23 - Paul Pritchard (Ballymena Academy)
24 - Gavin Nugent (Presentation Brothers College Cork)
25 - Jason Bloomfield (Coleraine Academical Institution)
26 - James McKinney (Campbell College)
Manager - Lorcan Balfe
Coach - Peter Melia
Assistant Coach - Paul Barr
Doctor - Ossie Fogarty
Physio - David Lyons