In the case we absolutely need to install a special Debian package, from backports for example, and force it to ignore dependencies using aptitude download and dpkg –force-depends, your apt-get and aptitude will always complain later on about it and not resume its given commands until we resolve this dependency.
So when you know what you’re doing and really want dpkg, apt-get, aptitude etc. to ignore the broken dependencies, there is a solution where the status of the dpkg system can be modified.
Simply edit the file /var/lib/dpkg/status and adjust it so that it will think that all is OK even with this broken dependency.
In my case I installed a backport python-subversion package where I didn’t want to install the subversion package since I compiled my own.
The solution was to simply delete the subversion part in the Depends: line of
python-subversion.

eg.
Before:
Package: python-subversion
Status: install ok installed
Priority: optional
Section: python
Installed-Size: 5624
Maintainer: Peter Samuelson Architecture: amd64
Source: subversion
Version: 1.6.12dfsg-6~bpo50+1
Provides: python2.4-subversion, python2.5-subversion
Depends: subversion, libapr1, libc6 (>= 2.7-1), libsvn1 (>= 1.6), python (<< 2.6), python (>= 2.4), python-support (>= 0.7.1)
.................

After:
Package: python-subversion
Status: install ok installed
Priority: optional
Section: python
Installed-Size: 5624
Maintainer: Peter Samuelson Architecture: amd64
Source: subversion
Version: 1.6.12dfsg-6~bpo50+1
Provides: python2.4-subversion, python2.5-subversion
Depends: libapr1, libc6 (>= 2.7-1), libsvn1 (>= 1.6), python (<< 2.6), python (>= 2.4), python-support (>= 0.7.1)
..................

WARNING: This is obviously a HACK and always remember to fix this back to normal before you do a dist-upgrade.