Instead of going through all that, why not just get the "Linux DEB" version?http://download.openoffice.org/other.html#en-US
Find your language in the Linux DEB column, download the corresponding DEB file, and just double-click it when it's done. The GDebi package installer should take care of the rest.
That's what i did, and I have had no problems so far.
Alternatively, you could just follow the instructions in this thread:viewtopic.php?f=42&t=18690
Once you've added the repository, run mintUpdate, and you should get an upgrade from 2.4 to 3.
Sarah 18 Cinnamon 64, dual-boot Win 10 Pro 64 SP1, Clevo W150ER 15.6" laptop, i7 3630M, 16 GB RAM, Samsung SSD 840 Pro 256 GB/HGST 1 TB 7200 RPM, Nvidia GT 650M 1 GB, eSATA 3.0 HGST 1 TB 7200 RPM, HP Photosmart C5280