Here's my .plumrc file:

    # for autoloading...  this dir has these scripts to autoload in it
    eval unshift(@INC, $HOME . '/scripts/plumlib')
    autoload repl_quick
    autoload repl_quoted

    bind + folder
    bind ^E repl_quick
    bind w reply_cc_all

    bind ^W repl_quick
    bind R repl_quoted

    bind ^R repl_quick
    bind ; reread
    bind A repl_quoted

    set mailcheck=5
    # set noautotype
    # set nocleanfolders
    set wastebasket=trashbox

    bind j down_line_sticky
    bind k up_line_sticky

    bind ( reply -e repl-quoted

Notice that it's in plum commands, not perl code, except for the
eval, whose presence covers a multitude of sins. :-)

One of the outstanding bugs in plum is that the keyboard input routine 
basically sucks.  You can't type control characters.  They have to read
in from a file.  Those caret+letter combos can really be control characters
in your plumrc file.

Notice the autoloaded functions, repl_quick and repl_quoted.  These are 
perl scripts somewhere in @INC.  Here's repl_quick.pl:

    sub repl_quick {
	&goto_message($Count) if $Count;
	&system('repl -whatnowproc repl-quick ', &current_msgid, $Current_Folder);
	&fudge_folder_id;  # anno updates
    } 

    1;

Here's another one, repl_quoted.pl:

    sub repl_quoted {
	&goto_message($Count) if $Count;
	&system('repl -editor repl-quoted ', &current_msgid, $Current_Folder);
	local($Auto_Type) = 0;  # suppress autoprinting of next
	&fudge_folder_id;  # anno updates
	&redraw;
    } 

    1;

There is much to be learned from these examples.  Good luck.