configuration you want is possible in Fixed Asset module. But in TRM product types and transaction are not assigned to company code.
If there is no any enchancement/user-exit you can follow this idea:
1. You make you number range for securities as external.
2. You create a Z* program: selection screen similar to the screen of the TS01, for example.
Here you enter all the data you need to create a deal. Then press enter. The program is looking for the latest number of the deal according to you creterias (let's say - 3112500001) and increment this number (let's say 3112500002).
Then Z* program passes all data from Z* screen (don't foreget to pass deal number) to TS01 transaction with Parameter ID and skip first screen - so the use won't see std.tr. TS01 screen.
the user will only see this
I hope you will understand what i wrote!