The following two scripts both create the API command !fly. The first script is functionally limited to the values 1-9, while the second script is not. However, the second script makes use of an API feature which may or may not be intentional, meaning that it might be broken by an update to Roll20 in the future.

Syntax

!fly [height]

Code: Version 1

on('chat:message', function(msg) {
    if(msg.type != 'api') return;
    var parts = msg.content.toLowerCase().split(' ');
    var command = parts.shift().substring(1);
    var selected = msg.selected;
    if(command != 'fly' || !selected) return; // use the !fly command, and have one or more things selected
    var height = +parts[0];
    if(!height) height = 0; // if no height is returned, treat as 0
    _.each(selected, function(obj) {
        if(obj._type != 'graphic') return; // only fly graphics
        var tok = getObj('graphic', obj._id);
        if(tok.get('subtype') != 'token') return; // don't try to fly cards
        tok.set('status_fluffy-wing', false);
        if(height > 0) tok.set('status_fluffy-wing', ''+height);
    });
});

Code: Version 2

on('chat:message', function(msg) {
    if(msg.type != 'api') return;
    var parts = msg.content.toLowerCase().split(' ');
    var command = parts.shift().substring(1);
    var selected = msg.selected;
    if(command != 'fly' || !selected) return; // use the !fly command, and have one or more things selected
    var height = +parts[0];
    if(!height) height = 0; // if no height is returned, treat as 0
    _.each(selected, function(obj) {
        if(obj._type != 'graphic') return; // only fly graphics
        var tok = getObj('graphic', obj._id);
        if(tok.get('subtype') != 'token') return; // don't try to fly cards
        tok.set('status_fluffy-wing', false);
        var wings = '';
        while(height > 0)
        {
            // get current digit, starting from ones
            var digit = height / 10;
            digit -= Math.floor(digit);
            digit = Math.round(digit * 10);
            // shift height
            height = Math.floor(height / 10);
            wings += 'fluffy-wing@'+digit+',';
        }
        if(wings.length > 0) wings = wings.substring(0, wings.length - 1); // trim trailing comma
        var markers = tok.get('statusmarkers');
        if(markers != '') markers += ',';
        markers += wings;
        tok.set('statusmarkers', markers);
    });
});

Notes

In the second version of the script, numbers with multiple digits will create multiple wing statusmarkers, one for each digit. Zero digits (for example, the tens digit of "205") will show up as a wing statusmarker with no number.