MZ: MultiHack does not introduce any compatibility problems at all. All MultiHack does is take an existing hack, that is normally posted in a TXT format or whatnot and automatically apply it to the necessary files. Any compatibility problems that may arrise will be between whatever version of UBB you are using and whatever version the hack you are applying was written for.
CreepingDeath: There is a documentation file included with the program that is in MS Word format. You can get to it from the start menu, program files. However the short of it is you need to visit
https://ubbdev.com/mhk and you will get a list of hacks in MHK format. Download the file you want. Double click the file you downloaded. It will automatically be imported into MultiHack and MultiHack will open up.
In the Options section of Multihack make sure that you have the "Source Directory" set to wherever you have your UBB files(always have a backup though!). Then set the output DIR to an empty DIR.
Now in the main multihack window, select the hack you want to install, click Install. All of the files that were modified will now be located in the Output Directory you specified in the Options. Upload those files to your web server and the hack should be installed.
iNtErNeT aDdIcT: More than likely you need to download the MDAC 2.5 SP2 files from Microsoft. The JRO files are used for the database. If you downloaded MDAC 2.6 instead, the Jet DB files are NOT included within that release they are a seperate download(which I have not installed so I have not given directions on how to do so).
If you have installed MDAC 2.5 SP2 or are having problems, please let me know what OS you are using(as freakscene said), if you installed MDAC already, what version. If you can't install MDAC, what errors you are getting.
Thanks much everyone!