It looks like requiremetns are:
Requirements:
vSphere SDK for Perl (formally VI Perl Toolkit) or VMware vMA 4.x/5.x+ (formally VIMA)
VMware vCenter 4.x/5.x+ and/or ESX(i) 4.x/5.x+
Looks like it won't work on your 3.5 hosts. This should probably be posted in the VCLI forum as William Lam usually posts in there i think.
Have you looked at Alan's Vcheck using Powercli?