First thing I'd do is to go back to the software vendor and tell them that you expect them to provide you with a licensing scheme that will support your enterprise virtualization strategy.
In the meantime, the best you can do is to use CPU affinity to pin the VM to a particular CPU. This will exclude the VM from VMotion and will also cause the vmkernel scheduler to penalize it with CPU scheduling.
Ken Cline
Technical Director, Virtualization
Wells Landers
VMware Communities User Moderator