Semi-manual Doxygen callgraph

Question

I'm using Doxygen to document a MATLAB codebase. Doxygen doesn't support MATLAB natively, so I am using the m2cpp.pl filter developed by Fabrice. The filter is good, but not good enough for Doxygen to automatically generate callgraphs and collaboration graphs. I have considered a few solutions.

Improve the filter

The most 'proper' option but unfortunately not worth my time. The filter is written in Perl, which I have almost no experience with. Moreover, I am documenting a legacy codebase that is unlikely to change and will soon be re-written in Python.

Manually write DOT

Doxygen generates diagrams by writing files in the DOT language, which are then rendered by Graphviz. I can add my own DOT files using the Doxygen \dotfile command. The DOT language is quite simple, so I can define the call & collaboration graphs that I want manually. However, this is tedious and leads to a lot of duplicated code.

Semi-manual approach

I was wondering if there is a middle-ground approach. I'm imagining a command that tells Doxygen which functions are called. For instance, in the code below I propose a new Doxygen command \calls, which would manually tell Doxygen that main() calls foo() and bar(). I know this would be a DRY violation and therefore error prone, but it makes sense for my situation where I am documenting legacy code that is unlikely to change. Could I do this by making some simple edits to the filter?

%> \brief Demo function
function result = foo()
    result = 1;
end

%> \brief Demo function
function result = bar()
    result = 1;
end

%> \brief Demo function
%> \calls foo, bar
function result = main()
    var_1 = foo();
    var_2 = bar();
    result = var_1 + var_2;
end

External callgraph generator

This callgraph generator supports MATLAB and returns a DOT output, but I'm not sure how I would include it in my pipeline. I would have to automate some process where it generates dotfiles that are automatically pulled into Doxygen.