You can receive your EPP key by logging in at my.xilo.net and clicking "domain list" on the right menu.
From the list of domains shown in the table, select which domain you wish to receive the EPP key for and click the small icon.
On the domain details page, you will have a button towards the bottom of the screen labelled EPP key. Click this once.
Your EPP will either be sent to the registrant contact of the domain within 1 hour, or shown to you on-screen.