Couldn't you just decompile the current plugin and recode it to work along the x and z axis instead of y? All you'd need is to decompile the plugin, change the code to make it work on the x and z axis then sign the package as a different package to avoid conflicts (for example instead of org.genbuckets.vertical you change it to net.beastfactions.horizontalbuckets).
Don't worry we have found a solution to it, also it is easier said than done, it needs to be tested for bugs etc. Later today/tomorrow ill be finalising the new feature their is a few bugs currently Once fixed ill add make it live .