I didnt saw good build for irelia in jungle, but she is the best jungler i ever seen. She got W for heal herself and nice def when gang lines.

Seals give you armor, its very important in jungle cause neutrals crips deal physical damage. Armor penetration quint gives you greater damage to minions and players when you will gang lines. Irelia make true damage from W skill, thats why important are atack speed runes. It let you to make more true damage to minions in jungle before coldowns on W come.

Masteries should gives you more resist in jungle, and in late when you will team tank or one of team ad/tanks. In early you got more mana refund from utilities masteries, and longer buffs.

I started with regrow pendant. Some of you can say: "lol?, wtf?" etc, but I really tested it and it work with that runes. Its great item when you are coming to another crips in jungle, you have faster regen heal, and when you wait in grass for gang line, you got more hp when gang will start.

Next item should be fast boots (mercury) and trinity force. When you got this 2 items, you should be have really nice damage with not bad defens.

Another should be warmong, for greater resists. Then atma gives you damage and resist, and banshee another tanky item.

The last item can be guardian angel but its not necessary. You can choose you own, for example win's end will be not bad.

Smite doesn't need to be introduce, but flash gives you few pixels more to escape from dangerous situation or if you are really agresive play you can use it offensive.