Yes, Google Apps can be used with MemberGate.
Most customers only use Google Apps for the email.
Google Apps will provide you with the MX records to add to your DNS settings.
The DNS settings can be edited in your Hostek control panel: https://wcp.hostek.com
Create a new DNS record
Click Add DNS Record button
Enter Name for record (If DNS record name is your domain name please leave this Name - text box blank as the control panel will automatically add your domain name)
Choose the Record type (A, CNAME, MX, NS, TXT, SPF, SRV)
Enter Data Type
Generally leave the TTL (Time To Live) as the default 86400
Click on the Save Icon.