doesn't make me angry at all, i've not seen a dedicated guide for this sort of thing, only picked it up from others. i now do this all the time, particularly with mildwild oxygen.
i would recommend using 7zip
- make a copy of the rom.zip, so you have something to compare, and a 'stock' backup in case you go wrong
- double click on rom.zip (which opens it, do not extract it)
- delete/replace system apps
- close 7zip to update the rom.zip
couple of other notes:
- don't delete important system apks, like settings for instance
- you can delete lots of other stuff, like languages you won't use(system/tts/lang_pico) and sounds (system/media/audio), saves a lot of space.
- i have found not all apps work on the system partition, they simply force close (don't know why). winamp, quickpic don't work for me, but most other stuff does like go launcher, go sms pro, jorte calendar, elixir. takes a bit of trial and error. you can always move them back and forth with titanium or something like SystemCleanup.
- once you've finished editing your rom.zip, you must make sure that your total system size is less than your hboot system size (<145MB if on cm7r2), otherwise it won't boot. you can check this with 7zip as it should show how big your system will be when extracted.
good luck, i find it more fun editing a custom rom before flashing...
Device: HTC Desire | Nexus 7
ROM: MildWild V-4.3 | Paranoid Android
Recovery: 4EXT Recovery Touch | TWRP
let's all try to get along ...but remember to search first...