How do I send a cfm file as the body of an e-mail using ColdFusion?

I have a legacy application where an email.cfm file is used with a cfmail tag to send e-mail:

<cfmail from="abc@123.com" to="def@456.com" subject="New e-mail!">
    // lots of HTML
</cfmail>

Now I'd like to update it for ColdFusion Model Glue 3. I want to send it using a mail object in the controller, and include in the body a CFM page:

var mail = new mail();
mail.setFrom("abc@123.com");
mail.setTo("def@456.com");
mail.setSubject("New e-mail!");
mail.setBody( ** SOME CFM FILE ** );
mail.send();

Does anybody have any idea how I can do this?

I ended up following Henry's advice in the comments and created a CFML-based CFC:

<cfcomponent>

    <cffunction name="SendMail">
        <cfargument name="from"/>
        <cfargument name="to"/>
        <cfargument name="subject"/>

        <cfmail from="#from#" to="#to#" subject="#subject#">
            <!--- HTML for e-mail body here --->
        </cfmail>
    </cffunction>

</cfcomponent>

Dave Long's suggestion is also good, which is to create components using <cfcomponent>, then wrapping the code in <cfscript> tags. This gives you the ability to fall back to CFML in case the there is no cfscript equivalent or it's easier to do with CFML:

<cfcomponent>
    <cfscript>
        void function GetData()
        {
            RunDbQuery();
        }
    </cfscript>

    <cffunction name="RunDbQuery">
        <cfquery name="data">
            SELECT * FROM ABC;
        </cfquery>
        <cfreturn data>
    </cffunction>

</cfcomponent>