Re: How to edit text in upload dialog for one group of users
Probably by editing the Smarty template (.tpl) file. If you have the Smarty template usage indicator on (under Admin -> Look & Feel) you can see what templates are being used if you view the source for the upload page you're wanting to change in the area where you'd like to add the text. Comments like this will indicate the template used for a section:
Then you can either edit the file through the tiki interface (turn on Edit Templates under Admin -> Look & Feel and a link will show in the admin panel and in the admin menu) or by editing the file on your server directly.