To install from source you can use:

sudo python ./setup.py install

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usage: picasasync [-h] [-n] [-D] [-v] [-m NUMBER] [-u] [-d] [-r]
                  [-t [THREADS]] [-o ORIGINS] [--max-size MAX_SIZE]
                  [--force-update [{full,metadata}]] [--delete-photos]
                  [--strip-exif] [--transform TRANSFORMS] [--delete-albums]
                  PATH [PATH ...]

Sync one or more directories with your Picasa Web account. If only one
directory is given and it doesn't contain any supported file, it is assumed to
be the parent of all the local albums.

positional arguments:
  PATH                  Parent directory of the albums to sync

optional arguments:
  -h, --help            show this help message and exit
  -n, --dry-run         Do everything except creating or deleting albums and
                        photos
  -D, --debug           Debug Picasa API usage
  -v, --verbose         Verbose output (can be given more than once)
  -m NUMBER, --max-photos NUMBER
                        Maximum number of photos in album (limited to 1000)
  -u, --upload          Upload missing remote photos
  -d, --download        Download missing local photos
  -r, --update          Update changed local or remote photos
  -t [THREADS], --threads [THREADS]
                        Multithreaded operation. Set number of threads to use
                        on album processing. If not given defaults to 1, if
                        given without argument, defaults to number of CPU
                        cores (4 in this system).
  -o ORIGINS, --origin ORIGINS
                        Timestamp origin. ORIGINS is a comma separated list of
                        values "filename", "exif" or "stat" which will be
                        probed in order. Default is "exif,stat".

DANGEROUS:
  Dangerous options that should be used with care

  --max-size MAX_SIZE   Maximum size of photo when using --transform=resize.
                        Default is 2048,2048.
  --force-update [{full,metadata}]
                        Force updating photos regardless of modified status
                        (Assumes --update). If no argument given, it assumes
                        full.
  --delete-photos       Delete remote or local photos not present on the other
                        album
  --strip-exif          Strip EXIF data from your photos on upload.
  --transform TRANSFORMS
                        Transform the local files before uploading them.
                        TRANSFORMS is a list of transformations to apply, from
                        "raw", "rotate" and "resize".

VERY DANGEROUS:
  Very dangerous options that should be used with extreme care

  --delete-albums       Delete remote or local albums not present on the other
                        system