To send a Custom Form Pack, use the same process as sending a Custom Form or Custom Web Form by opening the record to send from first and using the Send a Form option on the Action Menu:
Along with Custom Forms and Custom Web Forms, you will also see Custom Form Packs in the drop down list:
Select the Pack you wish to send and make sure the Custom Form Title (that will be displayed on the portal page is correct) and then click the Prepare button. This will create unique links for each of the Forms in the Pack and a single unique link for the Custom Form Pack itself:
To send this link in an email, click the Send & Save... button to open the email window. Select either a template or write your email text and use the Insert Form Link button to embed the unique link for the Pack into the body of the email: