specifically which commands do you need to send?
Once you have a connection with the matrix via RS232 or TCP/IP - you can sen them using the custom serial devices at the bottom of the catalyst control window.
(Try connecting directly via an RS232 port first to ensure that the commands work - before attempting via TCP/IP)
See pictures attached - this is an example for a kramer matrix - but the method will be similar for extron - just different commands...
I think some example commands are built in to catalyst at the top of the custom serial drop-down menu, but this may vary for your specific matrix
Eg: To perform a 'Quick tie' input 1 to output 3 for all audio & video on plane 1
[1b]'Q01*1*3!'[0d]
Multiple ties can be made in one command: input 1 to output 3 and input 2 to output 5 for all audio & video on plane 1
[1b]'Q01*1*3!01*2*5!'[0d]
S