usually, installing extensions under typo3 is as easy as can be: using the extension manager that is part of typo3, just choose 'import extension' from the drop down menu, choose the extension from the online repository or a local directory, and upload and import. the t3x file will be uploaded and unpacked into typo3conf/ext/directory. the extension manager will redirect you to another page where you can click on the 'install' icon - done.

sometimes, however, this procedure will not work for some reason: either a restriction on php regarding the size of files that may be uploaded, a limitation on shared memory on the server that can be allocated by typo3 - this sort of reasons.

the only thing that can be done then is manual installation. here are two ways to do so.

from local installation

suppose you have a local test server running (which is a wise thing to have), and a typo3 installation there. install the extension you want to use locally, just as described, using the extension manager. then set up an ftp connection to the remote server where you want to have the extension installed.

locally and remotely change to the typo3conf/ext directory and send the local directory containing the extension files to the remote server.

example: you have typo3conf/ext/cal with the calender base extension locally and want to have the calender on the remote server. suppose you are using the command line ftp client and are logged into the server. you just change to the directories as specified using lcd and cd commands, and then upload the directory cal using mput cal. uploading most likely will talke some time, depending on the quality of the connection, server load and the size of the file.

once the directory is uploaded, you can proceed using the extension manager. select 'install extension' from the drop down menu - the extension should show up in the list of available extensions together with the 'install' button.

from the extension repository

in the typo3 extension repository you will find the source files listed and linked together with the t3x files.

set up a directory locally that will serve as the container for all the single files you will have to download from the repository. this will be a bit tedious, but you will end up with exactly the same files you would have had in the corresponding directory of a local installation.

and obviously, after finishing the downloads the procedure is the same as described above: upload the directory into typo3conf/ext using ftp, and then proceed using the extension manager.