How to preserve your mods
1) Make a backup of your current files of your coppermine isntall to your local hard drive
2) Get a diff viewer like
WinMerge, install it on your PC
3) Get a fresh copy of cpg1.3.3, unpack it somewhere on your hard drive
4) Use the diff viewer to compare the fresh copy of cpg1.3.3 you just downloaded to your modified version you have downloaded in step 1
5) Note all the changes the diff viewer finds between the fresh copy and your modded version
6) Get cpg1.4.1 beta, unpack it to your hard drive and upload it as suggested in the docs that come with it (performing a regular upgrade)
7) If you have a custom theme, read the theme guide that comes with cpg1.4.1 to upgrade your custom 1.3.x theme to work with cpg1.4.1
8) Check that your new cpg1.4.x install works as expected, with all the new features that come with it (but not yet with the mods you applied)
9) Run the bridge manager (if you used to have your cpg1.3.x install bridged)
10) Again: check your cpg1.4.1 install: does everything still work as expected
11) Now that you have a working cpg1.4.1 install, it's time to re-apply the mods you used to have in your old install. For this purpose, take a look at the notes you have taken in step 5, and re-apply the code changes to your cpg1.4.1 sources
12) Finally check your cpg1.4.1 install: does it work as expected, with your custom mods in place?
I have to remind you once more: it's not recommended to use cpg1.4.1 beta on a production site, and it's only recommended for experienced users. If you feel that the above mentioned steps are to hard for you, then just don't perform the upgrade. Instead: wait untill the stable version of cpg1.4.x comes out. There is no support for cpg1.4.1 yet, so you won't be able to turn to this support board and request help fixing any issues that might turn up during the upgrade process.
This is just as much help as I'm ready to give on an announcement thread for a beta version; please don't post further questions to this thread about how to preserve your mods for cpg1.4.1 - in fact, if you don't know how to preserve your mods, you shouldn't even consider upgrading at all yet.