You should be able to do it with Import / Export commands from stsadm
export--
stsadm -o export -url "http://mysharepoint:port1/" -filename "d:\sitebackup\sitebackup.bat" -includeusersecurity -versions 4
Import --
stsadm -o import-url "http://mysharepoint:port2/sitecollection/subsiteurl/" -filename "d:\sitebackup\sitebackup.bat" -includeusersecurity -updateversions 2
Obviously replace the URL string with your actual URL you want to backup and restore. I have used this several times to do what you are asking for.