You can create custom objects to be used with custom assignee types in approval rules. This example will take a custom object called GO Approver and show how it is used to provide assignees when creating an approval rule.
Step 1: Create your custom object.
From Setup, go to Create > Objects and click New Custom Object. Create your custom object, adding the necessary fields to enable you to create a formula for selecting assignees. The API name for the custom object and its fields are what are used to create the custom formula in the approval rule.
Step 2: Make the custom object available to Intelligent Approvals via a custom setting.
From Setup, go to Develop > Custom Settings and click Manage for Approval Systems Properties. Click Edit and for UI Custom Assignee Object Types enter the name of the custom objects you want to use with custom assignees.
The Approval Systems Property must include the API name of the custom object:

Step 3: Create users for the custom object.
Go to the GO Approver tab to display the page and create all the users you want to approve requests. The values you enter in the fields for each user is what is used when you create formulas for selecting assignees.

Step 4: Create your approval rules, using formula expressions to select assignees.
Go to an Approval Rule of Type Condition and create assignees by selecting Custom User and then enter a formula in the Value field. For instance the following formulas would route an approval to the following assignees, based on the users you created for the custom object.
GO_Approver__c(ProductGroup_Pricing__c='AGRAPH' AND Level_Pricing__c='Level 0').aUser__c | Jim Borden |
GO_Approver__c(ProductGroup_Pricing__c='AGRAPH' AND Level_Pricing__c='Level 1').aUser__c | Oscar Borden |
GO_Approver__c(ProductGroup_Pricing__c='BGRAPH' AND Level_Pricing__c='Level 1').aUser__c | Jane Smith |
