I'll assume you wish this because there may be reasons you don't want to hook ESXi boxes to production switches, in fear you might "contaminate" the LAN and get spanked by your bosses.
The only time that I have heard vmware on direct peer-to-peer cables is when they are on 10Gb with SFP/twinax/copper to run vmdk's off shared storage, avoiding a 10Gb switch. Otherwise if worse comes to shove, do yourself a favor and find any plastic 5-port Gb switch from your home, work premises garbage, as Gb switches have been around for a good 20 yrs. Even the 4-ports on the back of an old router will work, albeit slower at 100Mb.
I've noticed things of vm network really like one another. They see each other almost immediately, and almost all the time too. If you had two ESXi boxes and one vCenter on the LAN, they all find each other.
