Are the only fields available for velocity scripting those that are in email scripting tokens?

Hi all,

I am trying to pull in fields from the User Object in Salesforce to populate signatures in my emails. Things such as the salesperson's URL, agents hours, license #. I cannot tell if these fields are being synced although Marketo help desk tells me that the User object is syncing. I've been told that to use these I will need to use Velocity Scripting. My question is, how do I know the field is available for use/ being pulled into Marketo? If I don't see it listed in the email scripting token would that mean it is not available?

Many thanks!

Erin