If you are asking if the modeler allows you to insert an HTML button, then yes. You can switch to HTML simple HTML tabs (see screenshot attached).

However, its functionality will depend on many factors; for example: 

1. Does the person receiving the message accept HTML messages?
2. Will the button function as a link to an external server page?
3. Did you want the button to do Laserfiche-related functions?

If #3 is what you are looking for, then it is my understanding that the Laserfiche email message allows you to "Approve/Reject" items using your email client or something, but I'm new at using Laserfiche and haven't actually tried that before.