\transpose weird staffs

[yota moteuchi]

Hi,

I have a nice horn in G part where in the middle it's written "from
here take your horn in E flat"
Of course in our orchestra we only have horn in F ^^
So I first entered the notes

hornpart = \relative c' {
\transposition g
... many notes ...
\transposition ees
.... again, many notes
}

And I'm now looking for the best and cleanest way to output the part in F
I tried to apply the \tranpose stuff using \skips (like using a global
staff for the layout) but...   it's a failure

any clue ?