Sql server sqllogship.exe...full docs and/or source code?
I am not sure of any other tool which you are referring to, but i prefer to use this sql logshipping app and yes its documented, refer to below article!

https://msdn.microsoft.com/en-us/library/bb283327.aspx

Not surprisingly, the sqllogship utility is specific to log shipping, which must be enabled and working in order to use the tool. The utility lets you perform copy, restore, and backup operations for an existing log shipping configuration.