I have only just gotten into creating roms, have had some success, this is what I do to create them... Figured this might start some conversations back/forth.
First, make sure you put the OliPro HardSPL on your titan so you don't wreck it.
Most of the tools below can be found searching with google and using the site tag "site
da-developers" in the search box. The main tools I use are tadzio's imgfs tools, bepe's pkgtool, and bepe's BuildOS (I have had to get BuildOS from one of the kitchens on xda-developers - have not found one separately)
Here is the approx order:
nbhtool or nbhextract - extract RUU_Signed.nbh into its component parts
nbsplit - convert the .nb of the OS above into .payload & .extra parts
imgfsfromnb - convert the .nb.payload into imgfs.bin
imgfstodump - convert the imgfs.bin into dump directory
pkgtool - convert dump directory into "packages"
This is where you modify and add stuff
pay close attention to initflashfiles.dat
Other useful tools for modifying the rom are G'Relloc (relocate modules from other hardware so it runs on the titan) and BuildDSM (creates DSM files for you).
BuildOS - "un-pkgtools" the dump directory into a new "temp" directory - needs to be run from the dump directory and needs to have a "tools" directory where some of the programs it uses lives. Also needs a copy of the boot.rgu from the XIP in dump/ROM/XIP (can be obtained using RomMaster and xipport tools).
imgfsfromdump - convert new "temp" directory into imgfs.bin
imgfstonb - convert new imgfs.bin into os.nb.payload
nbmerge - convert os.nb.payload into os.nb
nbhgen/nbhtool - convert os.nb back into RUU_signed.nb
I have sucessfully dumped the alltel rom, removed components, modified registry used packages from Pandora's Kitchen (you can find it on xda-developers) and the Apache WM6 Kitchen on this site and repackaged and installed it onto my titan without problems.
I have been a little vague on options used as it pays to understand what you are doing, and I am not necessarily sure I am using the best options and tools and although I had good sucess cooking with the alltel, my first attempts yesterday with the new sprint rom failed miserably.
I would like to get AKU .7 ported, but I have not quite figured out what that involves, can extract it, packagetize it, modify things, put it back into xip.bin, just don't know how to add it to the rom to flash back.
Hope that helps,
Geoff