Unreal Tournament 3 (DVD9 to 2x DVD5)
 

[1] Make folders DISK1 and DISK2, copy DVD content into DISK1 folder

[2] Move DATA CABS 6, 61, 7, 71, 8, 81, 9 to DISK2 folder,

only leave DATA CABS 1, 11, 2, 21, 3, 31, 4, 41, 5, 51. in DISK1

Copy all other files from DISK1 to DISK2 except

Launcher.exe
SetupUT3.exe
Unreal Tournament 3.msi

[3] Edit in notepad Autorun.inf in DISK2 to look like this

[autorun]
OPEN=0
ICON=Unreal.ico

[4] Download Orca from here and install it.

Press right mouse button over Unreal Tournament 3.msi and select Edit with Orca

On left you see tables list, select media in there, make these changes in colums on right window

Change DiskPrompt, by default its Please insert next disk

Disk1 or just 1 for cab files 1, 11, 2, 21, 3, 31, 4, 41, 5, 51
Disk2 or just 2 for cab files 6, 61, 7, 71, 8, 81, 9

Change VolumeLabel for Cab files 6, 61, 7, 71, 8, 81, 9 to DISK2

So the last cab ends with DiskPrompt: Disk2 VolumeLabel: DISK2

[5] Make PATCH folder to DISK2 for patches

[6] Make ISOs with labels DISK1 and DISK2, test with Daemon Tools and all emulation options on, burn your backup

Works on all versions (Install Sequence DVD1-DVD2 for All languages)

Thanks goes to Pitomon9000, just needed better translation :)

DiskPrompt can be anything you like so it can be Disk2, DISK2, 2, UT3_2 or DVD2.
When during install it will prompt you:

Please change the next disk: UT3_2

If you put UT3_2 in diskprompt for DISK2

VOLUMELABEL column is what counts and should be DISK2 for Cabs 6, 61, 7 and so on,
or if you want to label your isos like UT3_1 & UT3_2 you should change VOLUMELABEL columns for DISK1 to UT3_1 and DISK2 to UT3_2

Thanks for this guide, it worked 100%!!!