Seems to me you can as long as you connect it to an driveletter. Just configure it under Options -> Settings -> Catalog
I don't know what the performance penalty would be, if there is any. Your network speed will be an issue because you probaly will backup from that same network to which BE is writing its catalogs so your networkcard will be busy. Also it depends how far back in time you will need to restore backups. For example, there is no need to archive 1 month of catalogs when you only save 1 week of data and at the most only need to go back in time 1 weekt.
If you are low on diskspace adding a disk would be an option, after all what is the cost of diskspace these days.
Kind regards
A van der Boom