How to configure Leaflet for non-geographic WMS? - leaflet

Question

I'm trying to use non-geographic images stored in a WMS-service with Leaflet. These are images of old maps, that are not georeferenced yet..
I can't find the way to configure Leaflet to produce proper requests for WMS server. The problem is that BBOX values that Leaflet produces are not right. They are way too small and server responds with internal server error.
However, the server is functional and working well with proper requests.
This is the code for one map: (http://jsfiddle.net/fmL4x4fw/)
var base_url = 'http://warper.wmflabs.org';
var unwarped_image_width = 6708;
var unwarped_image_height = 6936;
var wms_url = '/maps/wms/177';
var map = L.map('map', {
crs: L.CRS.Simple
}).setView([300, 300], 10);
var southWest = map.unproject([0, 6936], map.getMaxZoom());
var northEast = map.unproject([6708, 0], map.getMaxZoom());
map.setMaxBounds(new L.LatLngBounds(southWest, northEast));
var mywms = L.tileLayer.wms(base_url + wms_url, {
format: 'image/png',
version: '1.1.1',
attribution: "warper",
status: 'unwarped'
});
mywms.addTo(map);
Should I write some kind of custom projection or is there some other way? I'm not very experienced with projections.
UPDATE:
This is how current implementation with Openlayers is configured:
un_bounds = new OpenLayers.Bounds(0, 0, unwarped_image_width, unwarped_image_height);
umap = new OpenLayers.Map('unmap',
{controls: [mds, new OpenLayers.Control.PanZoomBar()], maxExtent: un_bounds, maxResolution: 10.496, numZoomLevels: 8});
var unwarped_image = new OpenLayers.Layer.WMS(title,
wms_url, {format: 'image/png', status: 'unwarped'});
umap.addLayer(unwarped_image);