[Mediawiki-l] Secure Raw HTML and other preferences from install

[Azurite]

Hi all,
I'm trying to include a very small portion of raw HTML in my Wiki's 
Donate page-- just a PayPal button. But none of the default coding will 
allow it to display properly, so I'm thinking it's because Raw HTML is 
disabled by default. I've been reading that it's dangerous to enable it 
across the Wiki, so is there a way just to allow certain tags, or a 
small portion on a particular page, or pages ONLY edited by SysOps?

I'm not sure where I would go about changing the preference for the 
WHOLE Wiki if I had to in order to include the code, though I have a 
feeling that I would need to access that place for some other Wiki-wide 
preferences I was wondering about-- such as why the Talk pages are 
called "Discussion" on my Wiki. How do I access the preferences so I can 
play with these things (if necessary)?
-Azurite