I feel it's big challenging for MapGuide switch from OpenLayer2 to OpenLayers3. Let's look at the API documnets:
In OpenLayers2, OpenLayers.Layer.MapGuide constructor can accept params including mapDefinition, locale, mapName, session, basemaplayergroupname, format, showLayers, hideLayers, showGroups, hideGroups and selectionXml. So you can pass these parameters and manipulate your MapGuide instance; seeAPI doc: http://dev.openlayers.org/apidocs/files/OpenLayers/Layer/MapGuide-js.html.
However OpenLayers 3 design and re-write from scratch, MapGuide instance is ol.source.ImageMapGuide, it extend from ol.source.Image(version2 from OpenLayers.Layer), it accept a params object including ol.Extent, ol.Size, metersPerUnit, dpi ; see api doc: http://openlayers.org/en/v3.0.0/apidoc/ol.source.ImageMapGuide.html. I read the source code, I think probably to use this ol.source.ImageMapGuide.prototype.updateParams or try using ol._params_ to pass parameters. Myself haven't try yet, will try once I feel more familiar with OpenLayers 3.
ol2 to ol3 migration appears challenging, but only due to a lack of good examples. When I added MapGuide support to ol3, I could only add one example because I needed a known MapGuide Server that's publicly available, and that's the Autodesk-hosted one at data.mapguide.com
If you need extra guidance, you can check out the various ol3 examples I've bundled with mapguide-rest (https://github.com/jumpinjackie/mapguide-rest/tree/master/sampleapps). Although the examples work against the APIs provided by mapguide-rest, most of the APIs provided by mapguide-rest are just "clean URL" variations of what is already provided by the mapagent, so porting these examples back to vanilla MapGuide should't be too much of a challenge.
Re: Mapguide & Openlayers 3.12.1 Displaydpi for mobile/tablet devices
I will post my code once I can create a MapGuide Map with ol3, sencha to Github in the near future. I found ol3 has ol.control.* class to interaction with map, ol2 rely on DOM. Still feel lots to learn and practice.
I think OpenLayers 3 basically include everything I need for our mobile viewer to display our MapGuide map.
I do miss the function that called "redraw" for the layer feature.
I meant we can used updateParams to update the mapguide layer, but I still think redraw make my life easier haha.
I upgraded our mobile viewer (https://github.com/sreckolipovsek/KaliopaMobileViewer) from OL2 to OL3, and I wasn't able to understand all the OL2 selection/measurement methods written in original KaliopaMobileViewer. However, I realize that OL3 made my life easier to implement new controls, measurement and selection interactions. I don't care those geometry style too much as long as my mapguide layer are displayed the layer styled correctly. However, if you would like to draw something on the map, I don't think WebGL will help you... I think you can only use CANVAS to do that.