applying scaleDurations to a custom context

[Kieren MacMillan]

Hi all,

How can a make a custom context with a "built-in" scaleDuration  
factor? e.g. I have

  \context
  {
    \Voice
    \name CustomVoice
    \alias Voice
    \override NoteHead #'duration-log = #8
  }

Now, rather than writing

  myMusic = \scaleDurations #'(1 . 8) \relative { ...

I'd like to just write

  myMusic = \relative { ...

and then use

  \new CustomVoice \myMusic

so that the context compresses the music for me. What do I add to the  
context definition?

Thanks,
Kieren.