My data is stored in a hash, rather than an array, since I'm using specific indexes. I'm wondering what would be the easiest way to read this data into an Ext.data.Store?
Doesn't really matter how you store it - a hash table is no more than a 2 dimensional array that allows keyed access. You still have to pass an array of key/value pairs to the store. If you want to access the store data by key, make that you're id field; otherwise you can let it autogen the id and just store the key and value as fields of the store.