From the above messages, I assume we're talking Windows throughout.
Alert log
=========
I take it we're talking about the system alert
log in the bdump directory.
I've never come across this file being kept locked, but then I've never come across it growing fast enough to be a nuisance. Is Oracle writing to it continuously ? - most messages should just be log switch notifications - how fast is your alert log growing, how often are you switching logs ?
Listener.log
============
I take it we're talking about the TNS listener log file
log in the \network\logs directory.
Yes, this file will be locked by the listener service, but there are a couple of easy ways to start a new one.
a) since the listener is only used for establishing new connections, you can probably stop it for a few seconds without anyone noticing - rename/move the log file and restart the listener - a 3 line DOS script which you could schedule during a quiet spell.
b) schedule a "lsnrctl set log_file" command to change the listener log file name each day. This takes immediate effect and should let you move the old one elsewhere.
Hope this helps
Steve