I'm hate routine task. That's why I wrote a simple function to change svn:ignore propery on the current directory.

Add these lines in you .bashrc

function ignore()
{
    SVNIGNORE=/tmp/.svnignore
    svn propget svn:ignore . > "$SVNIGNORE"
    while [ -n "$1" ]; do
        echo "$1" >> "$SVNIGNORE"
        shift
    done
    svn propset svn:ignore --file "$SVNIGNORE" .
    rm "$SVNIGNORE"
}

Here is an example, how to use this script. Let's suppose, that you are in your working directory, and want to hide from SVN a 'packages' subdirectory and all files with .o suffix. Then you should run:

ignore packages '*.o'

Please, pay attention to the single quotes around '*.o', if you omit them, than shell will expand this pattern and only those files which exists on the disk will be added to the svn:ignore propery.