How to dynamically build and store complex linq queries against a list of hierarchical objects?

I have a list of objects in a hierarchical structure. I want to build complex LINQ queries against that object list based on "conditions" a client company sets and are stored in the database. So I need to build these at run time, but because they will be run repeatedly whenever the client's users update or refresh their data I would like to store the LINQ queries in objects rather than rebuild them each time.

I have looked at ScottGu's Blog about Dynamic LINQ.
Also this article about using expression trees.
Neither of these appear to provide an adequate solution, but I may not be understanding them adequately. I'm afraid that I'm trying to use LINQ when I should consider other options.

My object hierarchy:

WorkOrder[]
    Field[]
    Task[]
        Field[]

Here is an example of a LINQ query that I would like to store and execute. I can reasonably build this format based on the database records that define the conditions.

var query =
from wo in WorkOrders
from woF in wo.Fields
from task in wo.Tasks
from taskF in task.Fields
from taskF2 in task.Fields
where woF.Name == "System Status"
    && woF.Value.Contains("SETC")
    && taskF.Name == "Material"
    && taskF.Value == "Y"
    && taskF2.Name == "Planner"
    && taskF2.Value == "GR5259"
select new
{
    wo_id = wo.ID,
    task_id = task.ID
};

A few considerations.

• Depending on the complexity of the user defined conditions I may or may not need to pull from the different object lists: the "froms" are dynamic.
• Note that in this example I pulled twice from the task.fields[] so I aliased it two times.
• The example LINQ structure allows me to have complex ANDs, ORs, parenthesis, etc. that I don't believe is practical with Dynamic Chaining or Expression Trees.

In my code I envision:

//1) Retrieve business rules from DB. I can do this.

//2) Iterate through the business rules to build the linq queries.
foreach (BusinessRule br in BusinessRules) {
    //Grab the criteria for the rule from the DB. 

    //Create a linq to object query based on the criteria just built.
    //Add this query to a list for later use.
}

...Elsewhere in application.

//Iterate through and execute the linq queries in order to apply business rules to data cached in the application.
foreach (LinqQuery q in LinqQueries) {
    //Execute the query

    //Apply business rule to the results.
}

Thank you very much for your thoughts, effort and ideas.