Authentication to Eduroam on OSX is not difficult. Start by clicking the wireless icon at the top of the screen, near the clock. Then, click the eduroam network.
On the screen that appears, enter your myUMBC username, making sure to add the "@umbc.edu". Next, enter your password and click go.
That's it! You are now connected to the eduroam wireless network.
Once you have connected to the eduroam network, you should remove the UMBC Visitor and/or UMBC Campus networks from your wifi settings, or your computer could still try to connect to them under some circumstances. From System Preferences, click the Networks icon, then select Wifi from the list on the left, and click Advanced. Scroll through the Preferred Networks list to find the entries for UMBC Visitor or UMBC Campus, click on them, and click the - (minus) button beneath the list to remove that network.