Using .ckan files

If you use the CKAN mod manager then you can use a file that it automatically generates to tell KerbalX what mods you have installed.

Go into your KSP directory and into the CKAN folder.
Find the installed-default.ckan file and drag it onto the page and the mods listed in it will be added to this mod pack. (You can do this with any .ckan metapackage file.)

If you have multiple .ckan files (ie from different installs) you can drop them (one-by-one) to make a mod pack of the combined mods.