Assuming you want to do this via serial cable to a PC, you need:
1. A serial cable. Buy one as part of the HP connectivity pack
or from other sources, or make one
(see info at http://gauss.bu.edu/hazen/geos/ogo_serial.txt)
2. The omnicom program to transfer files. This runs on a PC under dos.
It is part of izl_ogsh.exe, which you can get from the IZL website
http://www.netaxs.com/~jferas/izl.htm or my website
http://gauss.bu.edu/hazen/geos.html
3. A file editor/viewer for the omnigo. I recommend Ray Schuler's
OgEdit. His terminal program OgComm and file manager OgFile
are also very useful. You can find them all at
http://www.usa.net/~schuler
All 3 take only about 40K.