[HTC Amaze 4G] KnowledgeBroker:
Instructions:

First, keep track of all the changes you want to make - the better organized you are, the easier this will be. If you aren't even sure what all you did..

How to do it:

One of the main things you are changing by creating a total prepacked rom is the build.prop- perhaps you have tweak A, and I have tweak B, and those tweaks are different enough to change the users experience.. but why not combine them if possible? It IS possible.

Decide on the build.prop edits that you want to add/modify(you will NOT replace their build.prop) and modify the propEditor script as needed - if you build for multiple devices I would recommend you add the device specific ones at the end(with #comments) for easy modification/removal from script. You really only need to MODIFY the RO.whatever lines(because they are read only), everything else can be added to a local.prop in the /data folder

Create your updater-script as you normally would, as you know this does the main work - this will likely remain mostly the same, with just a few lines added for the scripts you need to modify the build.prop. Just make sure you delete what you would from the rom itself with the script

Rather than copy your /system /data or any other files into the rom you would normally be modifying, those are the only files you will include in the flashable - if this is done right it will make all of the changes you want without breaking anything.

If you want others to be able to understand/build upon your work you can add #comments or a readme in the above steps, then all users would have to do is remove the lines you instructed, re-zip(no need to sign if they use 7-zip or winrar) and then flash.

As said in the previous area, outside the build.prop you can make a small flashable that will change everything, but if you can MODIFY tweaks already in the build.prop, or add lines if they don't exist-- we would be creating a continual evolution of a better and better performing rom.. with feedback bad tweaks would get tossed, each developer adds their flavor, but users can flash what they want to get the performance they desire without the headache and confusion that comes with wiping everything of the developer they used before that. This will enable them to learn more about how and what we are doing with their devices, and they can provide feedback that makes it better for everyone.

The code(that may need work) to modify or add lines in the default build.prop is here:

(This may require testing, big thanks to tommytomatoe for all the help, original thread is here.)

#!/sbin/sh

# Build.prop editor script with basic sed commands
# tommytomatoe
# May 12, 2012

# mounting system as rw
busybox mount -o remount,rw /system
if [ $? != 0 ] ; then exit
fi

FILE=/system/build.prop
TMPFILE=$FILE.tmp

line1=ro.product.version
line2=ro.HOME_APP_ADJ
line3=ro.media.enc.jpeg.quality
#Add more line# formatted as above as needed to identify each prop

line1Arg=Classicv0.1.0
line2Arg=1
line3Arg=100
#Add more line$Arg formatted as above as needed for each prop change

lineNum=

#to add additional prop changes copy the lines between here
prop=$line1
arg=$line1Arg
if grep -Fq $prop $FILE ; then
lineNum=`sed -n "/${prop}/=" $FILE`
echo $lineNum
sed -i "${lineNum} c${prop}=${arg}" $FILE
else
echo "$prop does not exist in build.prop"
echo "appending to end of build.prop"
echo $prop=$arg >> build.prop
fi
#and here and paste to the end, changing the $line# and $line#Arg to match what you've added

# to iterate over all the prop values you want to change,
# just copy and paste the code chunk or create a for loop.
# I will leave it to you to create a for loop

prop=$line2
arg=$line2Arg
if grep -Fq $prop $FILE ; then
lineNum=`sed -n "/${prop}/=" $FILE`
echo $lineNum
sed -i "${lineNum} c${prop}=${arg}" $FILE
else
echo "$prop does not exist in build.prop"
echo "appending to end of build.prop"
echo $prop=$arg >> build.prop
fi

prop=$line3
arg=$line3Arg
if grep -Fq $prop $FILE ; then
lineNum=`sed -n "/${prop}/=" $FILE`
echo $lineNum
sed -i "${lineNum} c${prop}=${arg}" $FILE
else
echo "$prop does not exist in build.prop"
echo "appending to end of build.prop"
echo $prop=$arg >> build.prop
fi

It may require some work, feel free to offer advice if you can help make it better), but you can make a few changes to that, and rather than replacing the entire system on a users phone, you are making YOUR modifications to make their device work better! Read the #comments above to see the different tweaks you are trying to make, and it will automatically either change the value, or it will add the line if it doesn't already exist in the build.prop