You can invoke lepton-attrib on your design from the command
line in the following way:
lepton-attrib file1.sch file2.sch ...
For example:
lepton-attrib my_design_*.sch
(This assumes you have a multi-page design with file names
my_design_1.sch, my_design_2.sch, etc.)
lepton-attrib will then read in your design, and present you
with a spreadsheet showing all components and associated attributes.
You can also just run lepton-attrib, and select the input
files in the “Open” dialog box.
To edit your attributes, just edit the cells in the spreadsheet.