I'm configuring few visual styles and putting appropriate cursors/sounds/ etc and making a .theme file.

I've opened the .theme file with notepad and saw that you can configure things like icons/cursors/sounds and even screen savers in there

Question is I'd love to set different loginUI for each different themes, so is there any parameter for setting loginui.exe desitnation inside .theme file? looked at MS technet but no luck

thanks in adv

No. Not via theme. But you could make a batch that executes the below reg file and sets the theme.

Ok. Make a blank logonui.reg file and put
The entry here has to be hard-coded to a fixed drive, so if you want variables, you might use an inf file? Or REG ADD entries?
I don't know what determines which .theme file to use. This logonui trick won't work from the Display Properties in the control panel
Edit: and also Technet only have more technical stuff, not theme files.