Looking at this chart, it looks like it isn't supported. The closest match I saw had a disclaimer for supporting only specific versions of iDRAC 6. It appears that the DRAC5 is just too far back. [URL]
I have spent a number of days trying to setup OME to monitor our network, which consists of a large number of older PE2950's.  They are all running ESXi and DRAC5.  OME is able to to inventory them via SNMP, but I can't seem to get WSMAN to get any information. Dell TT shows "Not recognized Error" for WSMAN on the DRAC IP's, and WinRM gives: "Error number: -2144108269 0x80338113 The WinRM client sent a request to an HTTP server and got a response saying the requested HTTP URL was not available. This is usually returned by a HTTP server that does not support the WS-Management protocol." I tried installing OME1.3, where DRAC 5 still shows as supported.  I was hoping to use some of the System Update functionality on these servers ... but I'm starting to feel perhaps DRAC5 just never supported this?    
Is it possible to use WS-MAN for DRAC5?