I have a Visualforce page that displays a number of records in a data table with a checkbox in each row. As can be seen in the code below

<apex:page controller="ProgramSupportList">
    <apex:pageBlock >
      <apex:form >  
        <apex:pageBlockTable value="{!ProgramSupportItems}" var="psi">
            <apex:column >
                <apex:facet name="header">
                    Select
                </apex:facet>
                <apex:inputCheckbox value="{!psi.id}" />
            </apex:column>        
            <apex:column value="{!psi.id}"/>
            <apex:column value="{!psi.Status__c}"/>
            <apex:column value="{!psi.Date__c}"/>
            <apex:column value="{!psi.Hours__c}"/>
            <apex:column value="{!psi.Program__r.Executive_Coach__c}"/>            
        </apex:pageBlockTable>
        <apex:commandButton action="{!ProcessSupportItems}" value="Invoice Selected Items" />
      </apex:form> 
    </apex:pageBlock>
</apex:page>

What I don't know is how to set up the ProcessSupportItems method to grab those values and pass them to a static method.

Here is my controller code 

public class ProgramSupportList {

    public PageReference ProcessSupportItems() {
         List<Program_Support__c> ml = setCon.getSelected();
         System.Debug('************1');
         System.Debug(ml);
         System.Debug('************2');       
        return null;
    }

    
  // ApexPages.StandardSetController must be instantiated 
    
  // for standard list controllers 
    
    public ApexPages.StandardSetController setCon {
        get {            
            if(setCon == null) {                
                setCon = new ApexPages.StandardSetController(Database.getQueryLocator(
                       [Select Id,Status__c,Program__r.Executive_Coach__c,Date__c, Hours__c From Program_Support__c
                        where Program__r.Executive_Coach__c = '003V0000001y6nC' 
                        AND Status__c != 'Invoiced'
                       ]));
            }
            return setCon;
        }
        set;
    }

    // Initialize setCon and return a list of records 
    
    public List<Program_Support__c> getProgramSupportItems() {
         return (List<Program_Support__c>) setCon.getRecords();
    }
}

I have noticed that the button does not seem to be calling the method as I don't see any of my debug statements. So that may be the issue.

NOTE: I eventually did resolve the problem using the wrapper based solution. One thing that was causing a problem for me was also this line of code:

<apex:inputCheckbox value="{!psi.id}" />

While it did not generate an error it would not allow any command buttons to properly call the APEX methods. Turns out its not a good idea to bind a checkbox to a read only field as I did in this case :) .I fixed this using code similar to what was presented below in the solution by incorporating the wrapper and binding the checkbox to a boolean field.