You can download the source package from our repository extract it and inside there should be a debian folder. And if you would like to update a package it could be enough to copy debian folder to new source code folder. Depends on how much were changed from source. Then you only need to update the changelog to a new version.
If you need other build dependencies you could edit the control file.
The configure command can be found in the rules file.

To rebuild such a package in scratchbox you only need to type.

One problem with newer debian packages is that they require newer build or configure tools, which our autobuilder doesn't have.
Then you need to start to downgrade the requirements which could be really pain.

However on device development you are more flexible and could also install things you can't upload to our repository.
The same is when you are using some package from cssu for compiling a new package, then you can't upload it to our repository, thats why I uploading some packages to openrepos.

The biggest showstopper is our old glibc. Some nice newer debian packages need newer glibc which will not happen with maemo5 and this is also one of the reasons why maemo leste gets created.