Sorry I did this a while back when the ability to transfer lsp files to xlights was active and to be honest, can't remember how to do it. There is a thread in the forum explaining it. I remember I primarily brought across only the megatree and spiral tree effects to see if it worked, which it did but created quite a big file (128mb xml file) compared to the usual small xlights created xml files. Also, I understand there is more than one way to import it and the way I did it means you can't edit the effects once in xlights. However, I think there is another method via data layer importing that might make the effects editable in xlights once converted but others would be able to direct you better - I'm still a bit of a noob when it comes to xlights so I'm still getting up to speed with all the things this excellent program can do.
It did however bring across all the images and effects I had done on the megatree so it certainly worked ok. I just didn't end up doing the full conversion because my wife said three years in a row for that sequence was too many so i left it alone. Might look into using it and updating it next year. If I figure out how to do it again, I'll let you know but I'm sure you will have been given the info by the more knowledgable by then.