custom access??

hi, i have a mac OSx 10.6.2
im trying to install the ViaCAD 2d/3d but it says
"this installer requires admin privileges to run"
i tried the get info and it says "custom access"
what do i need to do to install this software?
thank you

Is the computer you are trying to install ViaCAD your computer? Or do you use an account on your parents/siblings computer?

the computer is mine, im the admin and only user

Does it ask for you password and user name?

yes it asks for a password.
i entered the password and unlocked the padlock
the users and privileges box does not highlight and i cannot make
changes to them.

I'm stumped on this one.. I'll keep thinking about it and post if I get a idea, sorry.

ok, please help if you can
thanks