Hey seabird,
From the command line set your oracle sid then type in the svrmgrl command. also if you type in lsnrtcl from the command line you can check your listner and start and stop it.
It doesn't matter if your listener is down or not, you should be able to get to the svrmgrl command.
set ORACLE_SID= your_sid

Remember what mrchrispy said, the important thing is to get your database backup and accessable to the users. Which means as long as the listener is up and running with the database. The other OEM stuff you can take care of later.