I have 2 spare older Cisco Catalyst (not Nexus) 5500 switches. Would I need any additional hardware in order to run Fibre Channel over Ethernet (FCoE) over them? Do I need some kind of management device and/or software or can I do that internally? I'd like to re-purpose the old switches for a lab, but I'm unsure of the FCoE requirements and compatibility.
My knee jerk reaction to this would be to say "don't do it." Mainly because these switches would not support data center bridging. FCoE is not like iSCSI. FC is a bus and assumes it is lossless. Ethernet, as you know, is lossy. DCB allows Ethernet to act lossless and transport FCoE frames.
I think that any switch you run FCoE on has to support 802.1Qbb - priority based flow control, which allows Ethernet to act lossless much like FC.
Unfortunately, no, you can't. Specifically because FCoE requires lossless Ethernet, which can't be done on a Catalyst 5500. PFC works on physical ports, but the switch itself needs to have internal VOQs in order to not lose frames from port to port internally. You can do old-timey flow control on a 5500 which will keep physical ports from overflowing each others buffers, but it won't guarantee losslessness on internal ports.
Also, the switch wouldn't support FIP, which is the control plane for FCoE.