Create an empty perforce changelist in p4python and save the changelist number

create_empty_cl.py

from P4 import P4

client = P4()
# set client.port, client.client, etc here
change = client.fetch_change()
change['Files'] = []                    # this contains all the files in default otherwise
ret = client.save_change(change) # ['Change 1234 created.']
new_cl = ret.split()[1]

# now you can do stuff like
client.run_add('-c', new_cl, 'path/to/file.txt')
# or
client.run_integrate(['-c' + new_cl, '//path/from/...', '//path/to/...'])