Question concerning installing a local port

[Marko Käning]

Hi,
 
I have a local port repository which I use for updating existing MacPorts ports locally.
 
I usually do extract/configure/build/destroot as non-admin user, only the last step, meaning install, I want to execute as the admin.
 
If I run "sudo port install" then - of course - other directories are assigned for storing the downloaded files, build directories, etc.
 
What I'd like to achieve is to tell the sudo'ed port command that it should use the directory structur of the non-admin user. (My tries with -D option didn't work as expected.)
 
How to do this properly?
 
 
Greets,
Marko