Attached Link: http://www.unwrap3d.com/

No you can do it. I think maybe look at Unwrap 3d.I think it's $10, Reasonable anyway and way more powerfull than UVmapper. There is also other programs around and if you can't do it direct then do it indirect as in convert paint, convert back. What kinda files you trying to paint? The only one that is a pain is .max files and one other one that's sorta weird but can be done is .3dmf files