I recently went through the Motec installation, I don't remember of specific problems.
I downloaded and installed the latest version of Motec from here
I installed in C:\Motec, but I guess it could go in a different place.
Then I downloaded & installed the Motec plugin (as far as I remember it doesn't come with i2Pro). You have all info about it here
Following the instructions on this last page I don't think that I had any issue. You can then edit the MotecPlugin.ini file to configure it the exact way you want.
One point though: if you want to put the Motec log files in a given folder , make sure that when you specify the folder name it ends with \ (backslash) (just like in the example provided by 57goldtop )
Hope this helps