see :
Pro/INTRALINK 10.0 F000 - M040 Data Migrator Compatibility Matrices
http://www.ptc.com/WCMS/files/127205/en/10_0--M040_ProINTRALINKDataMigratorCompatibilityMatrix.pdf
Pro/INTRALINK 3.x Migration Planning Guide
http://www.ptc.com/appserver/wcms/standards/fileothumbredirect.jsp?&im_dbkey=128262&icg_dbkey=522
There is no need to 'upgrade' Oracle in steps. You have to install a fresh copy of the latest/supported release of Oracle as part of the new installation (on another server). Then use the data migration tools & process to copy the file vault contents and migrate the database content from Intralink v3.x to Windchill v10.0.
You should clone the current Intralink v3.x system first and use the cloned copy as the source for migration, as you will need to rehearse the migration process a few times before you can do it for real without getting stuck. We did 5.5 complete rehearsals (the last half one was repeated from a VMWare snapshot to confirm timings).
There is no option to upgrade in place on the same server, so you will need to get hold of another server or two..., so its far better if you can get your IT people to setup a VMWare host, as then you can have several test servers and the benefit of 'snapshots' to revert to earlier steps when it goes wrong. Hosting on VMWare is a certified & supported platform for Windchill, but do check the licensing for Oracle very carefully - you will probably end up deciding to put Oracle on a seperate physical server.