Linq Convert to Custom Dictionary?

Question

.NET 4, I have

public class Humi
{
public int huKey { get; set; }
public string huVal { get; set; }
}

And in another class is this code in a method:

IEnumerable<Humi> someHumi = new List<Humi>(); //This is actually ISingleResult that comes from a LinqToSql-fronted sproc but I don't think is relevant for my question
var humia = new Humi { huKey = 1 , huVal = "a"};
var humib = new Humi { huKey = 1 , huVal = "b" };
var humic = new Humi { huKey = 2 , huVal = "c" };
var humid = new Humi { huKey = 2 , huVal = "d" };

I want to create a single IDictionary <int,string[]>

with key 1 containing ["a","b"] and key 2 containing ["c","d"]

Can anyone point out a decent way to to that conversion with Linq?

Thanks.