Not directly, but you can use ```get_symbology``` to convert your code (ISIN, CUSIP, SEDOL, street ticker) into a RIC:
tr.get_symbology(['AAPL', 'IBM'], from_symbol_type='ticker', to_symbol_type='RIC')
and it will return something like this:
RIC primaryRIC
AAPL AAPL.O AAPL.O
IBM IBM IBM
Yes indeed. If you are using Datastream, you could retrieve ISIN codes for your Mnemonics in Excel and then use the ```get_symbology`` to get to RICs...