Thread index on custom headers

I've been trying like crazy to get MHonArc to do something which I can't
figure out if it is even possble.

In Short:

        I want a "Subject" like thread index on a custom header.

In Long:

        Let's say I've got a system which embeds a account number header
into mail.

        From:    Michael Gwilliam <michael(_at_)mail(_dot_)e-glyph(_dot_)com>
        Date:    Sun Mar  7, 10:12pm -0500
        Subect:  locked self out of car
        To:      fred(_at_)e-glyph(_dot_)com
        Acct:    A1234


No I want MHonArc to make me a list like:

        * Account A1234, locked self out of car

            * <Possible follow-up(s)>
            * Acct A1234, Re: locked self out of car
            * Acct A1234, Flat Tire on car
            * Acct A1234, Re: Flat Tire on Car

        * Account A287, locked self out of house

            * <Possible follow-up(s)>
            * Acct A287, Re: locked self out of house
            * Acct A287, Broken Swing on porch
            * Acct A287, Re: locked self out of house

In other words I want to group messages by a custom header within MHonArc.

If someone could tell me this is or isn't possible I'd be very thankful.
I can think of work arounds like translating the Subject line, but
I wanted to know I haven't missed something first.

(I wouldn't mind knowing how to do it either, but I don't want to bother
anyone to try to figure it out.)

Thanks a zillion,

Michael

-- 


Michael Gwilliam
michael(_at_)e-glyph(_dot_)com
pager 917-788-6938