New Chapter within an MM document

[Damian McGuckin]

Within an MM document, a level 1 heading like

        .H 1 "Heading"

is rendered as

        4. Heading

Often, it is forced to a new page using

        .nr Ej 1

I would like also to currently force it to

        Step Down N lines
        Move Right M spaces
        Prefex everything by some text such as Chapter

so it says something like

        Chapter 4.  Heading

Has anybody done something similar?  I tried to use heading customization 
macros but have gone nowhere fast.

Just thought I would ask the group before I jump back into the fray in 
case somebody has already solved the problem.

Using another Macro set is impractical.

Thanks - Damian