If you are unable to do this yourself you'll probably be needing to look for some kind of commercial help. I seriously doubt that anyone is going to d/load the modules, merge the code and supply it to you out of the goodness of their heart.
Before giving up on your own attempts though, exactly how are you going about doing the merge yourself? Are you using a text editor and trying to copy/paste the code, or are you using the proper tool for the job (eg: Kdiff3, Winmerge, etc, etc).
If you've not tried using these tools before, then now is a good time to learn.
Another tip that you may find useful is to first identify which of these two modules make the most changes to the core code and use that modules modified code for you 'base', and then merge the other modules code into this 'base' code.
By doing it this way you are effectively only needing to merge one file into the other, and the original zencart code can be ignored.
This of course assumes that the module(s) contain premodified code (as most do).
The hard way of doing things is to merge the code from both modules into the original zencart code.
Hopefully you find this useful.
Cheers
Rod