On 350 I don't know. On 650, 665, One, 900... it's possible.
One key have only one command but we have a lot of keyboard keys and we can create a lot of screen keys.
I don't remember exactly how to do, I create the scripts a few years ago but it's easy to do : we create a little script which have a name and we affect this name to a keyboard key (I think) or to a screen key (I'm sure) :
For example, when I want to look up at an external disk I've plugged, I've written all the commands which allows me to go to /media/. It avoids me to type several times on the keyboard and it's quicker. As I don't remember all the commands, it's an example :
go to home # home is defined to /movie/
enter # OK key
enter
go down # the down key
go down
enter
go down
enter