Tweaking stock Messaging app

[Guest taffer]

I originally posted this on the xda-developers forums, but it got locked before anyone could help for some reason unknown to me, so I'm hoping you guys can help me out.

T-Mobile USA has a 300KB limit on its MMSes, and the stock Messaging app on the Nexus One has its limit set to 1MB. This is an issue because if I take a high resolution picture, it is almost definitely over 300KB. Usually, it'll be around 700KB, which then fails to send because of its size. Occasionally, the photos will be over 1MB, which triggers the app to compress the images, but this also results in a picture over 300KB.

Yesterday, I did some poking around in the Android source (I'm very new to Linux and Android development, so it took me a while) and found that the 1MB limit was in a resource file. "This is going to be easy!" I thought to myself, but then I found out that it wasn't easy at all.

I made the change to 300KB and compiled the entire source with the "make" script. An hour or two later, it finally finished. Through some Googling, someone had made a post in a different forum pointing me to the apk in the "out/target/product/generic/system/app" directory. I then pushed the Mms.apk file to my phone and that's where I'm stuck; it doesn't work.

I don't even know if this is how I'm supposed to be doing this. If someone point me in the right direction, I'd really appreciate it. And if you're locking this thread because I'm breaking some rule that I'm not aware of, please educate me on the reason why :)