Trouble installing from Remote Disc
How about:


On the Ubuntu machine, make a ZIP file of the installation package.
Copy this file across to the Mac, using your existing sharing setup.
Expand it on the Mac and run it.


Edit
The actual solution can be found in the comments below: use sudo mkdir /media/test; sudo mount -t hfsplus /dev/cdrom /media/test to mount the CD on the Ubuntu machine.