I've heard of foobar but never tried it. I am a mediaMonkey lover through and through, and more concerned with managing my music well that with audio perfection.
If you find any information on an html interface, please post them and I'll consider adding something. If there are keyboard shortcuts that you can use then you might be able to rig something with VoxCommando's sendkeys or inputkeys commands.
Also, I think that eventGhost has a plugin for foobar, and since Vox can easily send commands to eventGhost, that might be your best options. When I first created VoxCommando, it worked exclusively though eventGhost, and I still do most of my stuff though eventGhost. I have been trying to expand the direct connection to other software partly to make life easier for new users, or people who don't feel comfortable messing around with a lot of settings and configuration with multiple programs, and also to get better control over programs and access to media library information, like in WMC or XBMC.
I suspect though from looking at the commands available in the EventGhost-foobar plugin that foobar can only be contorlled via "sendmessage" commands in windows, which means it can only do limited stuff like, pause, play, volume, etc. and does not allow you do queue specific artists or albums etc.