When looking at the apps in Titanium Backup, the MMS program may be called "messaging" or something like that, I do not recall exactly. It does not specifically say mms.apk.
Here is a link to a cyanogen 6 mms.apk that I tested as working.
I always have to reboot after uninstalling the first messaging app to install the cyanogen mms.
I read some where that GO SMS has a user agent option, if you are willing to use that program it may be a much easier fix for the blurry MMS pics.
If you do choose to uninstall the default messaging app, those funky white button icons are not going to be around anymore.
i see 2 files in TB that I think you are talking about. I am not sure which one it is tho, although i think it's the first one. PLMK if i am correct.
sms/mms prefs - messages 1.00
sms/mms/apn - dialer storage 2.2