Maya running source plugin (see below) and fbx plugin, SFM, Source SDK
Optional: Another animation programme of your choice.

Tips: If you get no animation in Maya when importing then you need to bake your animation, with motionbuilder it's done with the plot option, in 3dsMax you can just export to SMD then re-import it. Or check you have removed your namespace if you applied one.

This method can also be applied to props.

To run Maya with the plugin enabled, you must start Maya with the bat file in your steam\steamapps\username\sourcesdk\maya\version\ folder Then to enable them, in maya go to window - settings/preferences - Plug-in manager. and check vstUtils.mll, VsMaster.mll, vstSmdiO.mll, fbxmaya.mll