In its settings directories KTorrent stores symlinks to currently downloading files.
I put download into my home directory e.g. /home/myname/somewhere then symlinks in settings directories are absolute: /home/myname/somewhere.

Could it be possible to make them relative if download is in my home directory: e.g. ~/somewhere?

No the symlinks are already gone in the version for KDE4, I'm not gonna mess around with them anymore.