global class ID_ApprovalSchedulable implements Database.Batchable<sObject>, Schedulable {

global void execute(Database.BatchableContext oBatchableContext, List<cms__Approval__c> oApprovalBatchChunkList) {
    System.debug('>>> ID_ApprovalSchedulable.execute(Database.BatchableContext ...)');
    System.debug('=== ID_ApprovalSchedulable.execute(Database.BatchableContext ...): `oApprovalBatchChunkList.size()=' + oApprovalBatchChunkList.size() + '`');
    System.debug('=== ID_ApprovalSchedulable.execute(Database.BatchableContext ...): `oApprovalBatchChunkList=' + String.valueOf(oApprovalBatchChunkList) + '`');

    // get the work item list
    List<ProcessInstanceWorkItem> oWorkItemList = [SELECT ProcessInstance.TargetObjectId, ActorId FROM ProcessInstanceWorkitem WHERE ProcessInstance.TargetObjectId IN :oApprovalBatchChunkList];
    System.debug('=== ID_ApprovalSchedulable.execute(Database.BatchableContext ...): `oWorkItemList=' + oWorkItemList + '`');

    // auto approve the items
    for (ProcessInstanceWorkItem oWorkItemCurrent: oWorkItemList) {
        Approval.ProcessWorkitemRequest oPWR = new Approval.ProcessWorkitemRequest();
        oPWR.setComments('Auto approved through JobId: '' + oBatchableContext.getJobId() + ''');
        oPWR.setAction('Approved');
        oPWR.setWorkItemId(oWorkItemCurrent.ID);
        Approval.ProcessResult oPR = Approval.process(oPWR);
    }

    System.debug('<<< ID_ApprovalSchedulable.execute(Database.BatchableContext ...)');
}

...