At View/Preferences I choose on the tab Media at 'Playback' for Custom command line.
At custom command line I filled in:
"H:\Program Files\foobar2000\foobar2000.exe" "%1"
At Custom enqueue commennt line I filled in:
"H:\Program Files\foobar2000\foobar2000.exe" /add "%1"

But H is my section of the harddisk, in your case it could be something else...

At known media files I filled in:
mp3;wma;wav;ogg;m4a;shn;flac;ape

I hope this will help you...