as @Leo says, it's quite simple to add your button, just read the help.
/home\dopusrt.exe /col import /utf16le /create "My_Txt" {f}
Go NEWTAB=findexisting PATH=coll://My_Txt OPENINDEST
it's already there:
https://resource.dopus.com/t/command-selectex-extended-select-command/20517