I am not sure about optware packages, but I know of two opensource packages for debian(for linux really) that do what you want;Motion and Zoneminder. Of course nothing can compare to Synology surveillance station. Nothing that is free and open that is.
What you can do is run chroot environment on your router to run the whole debian environment.(Note: it needs to be of the same cpu architecture) And then just install any packages like on normal debian. However, you would also need kernel modules to support your USB webcams.
You would have to setup a compiler either on your router or desktop linux machine, to compile/cross-compile kernel modules that you need. The former is a lot easier as long as optware has all the packages to install compiler and setup the environment(it should)
I would nicely ask Merlin about them, maybe he already have them compiled. He might even have them hosted somewhere on his website or github.