I agree with Michael Chandra; The Matrix in 6th Edition might as well be Magic, and trying to treat it like modern tech is a pretty common pitfall from what I can tell.
I saw this with some of my veteran buddies when we were playing back in the 90s; "these ranges are all over the place", "I want to build the demo charge like this", "can I make my own weapon mod that does x?", and so on.
My observation is that if a player possesses in-depth knowledge of a particular subject they will often, knowingly or not, impart that knowledge into their Player Characters. When that happens, my personal rule of thumb is three-fold;
1. Are there any existing rules I can use for what the character is trying to accomplish?
2. Is it a cool and/or creative idea?
3. Does it further the plot ("yes, and" type improv)
If the answer to any of the above is true, I'll try to come up with a way to integrate the players idea into the storyline.
For example, in this case, let's go through what the player was asking, and note that I am paraphrasing here:
"I've hacked this commlink; can I track it and/or spoof it at a later time?"
1. Existing rules
Each net hit on Matrix Perception allows you to ask one question about the device in question. "What is it's commcode" would be a valid question in this case. This is really all you need to then later specifically use Matrix Perception again to find the device; this in turn lets you target it for Spoof Command (only needs Outsider access) or for Trace Icon (requires admin access, if memory serves). So the rules already cover what the player wanted to be able to do, and his actions are technically redundant; he doesn't 'need' to write a screamer to do what he wants, but let's move on to the other two questions, shall we?
2. If the rules already cover what he wants to do, the act of creating a screamer file (I would personally call this a program, but that's just preference) could be seen as a narrative explanation for the player characters actions. Mechanically speaking, it's no different from the a Tual rules, but if it makes your player happy to come up with some technojargon for how he does what he does, all the more power to him, right? Well, that's where the third question comes in.
3. How does this action further the plot? Only you can answer this, but I see two distinct possibilities here; the player uses resources at their disposal to come up with a cool, narrative way of tracking down who their contact is. This could be a whole story arch in itself, when they discover that their company woman is actually second in command of UCAS military training operations in Seattle! Alternatively, if I don't want my players to learn that particular detail just yet, guess what; this is a skilled company wan, and she burned that commlink the moment she walked away from the meet.
Just how deep the rabbit hole goes is entirely up to you, the GM. I'm a firm believer in enabling my players to have fun. Even if something they want to do isn't covered by the written rule, it can be a good idea as a GM to go with the flow and let players help you build your narrative. As a player, I love when things I think of can help shape the story we are telling; being empowered by a GM who takes my wacky idea and runs with it is a great feeling.
tl;dr
I wouldn't worry too too much about what the rules say and what they don't; the ultimate goal is to have fun, and as long as you are consistent with regards to implementing the rules and game mechanical at your table I think you'll be just fine.