If you have a current maintenance agreement with HP, then I can imagine HP might be willing to work with you to get you a copy of QC8. It would depend on the circumstances of your needs. Though, if you had a current maintenance agreement, why wouldn't you consider using QC10?
So why QC8?
"The single biggest problem in communication is the illusion that it has taken place."
-George Bernard Shaw, Irish playwright and Nobel Prize winner, 1856-1950
Your only source is HP. They will validate a number of items
<ul type="square">[*]Is your maintenance contract current?[*]Do you have an active support agreement?[*]Did you originally have QC8 in your enterprise as a purchase?[*]Have you upgraded your existing QC instances? IF so, why would you be downgrading (and this has severe database consequences)[*]...[/list]
If you are looking for a trial, or a pre-purchase evaluation, then you can work one-on-one with any HP Mercury Salesforce member or VAR. They will work with you to evaluate the current release. "Trial," or time-and-session-limited-pre-purchase-evaluation, licenses for prior releases are not available unless you are downloading these earlier releases from a pirated/broken software site along with broken keys.
You have piqued my curiosity, why is it that you seek an evaluation of such an old release, when if successful you would not be able to purchase that release....only a new release? Your request is unusual to be sure.