How To Make AIM Mandatory??

[Heineken77]

Hi,

How do I make the profile field AOL Instant Messenger Handle: mandatory? I went to User Profile Fields > Edit however the only fields available to me to edit are the following:

Biography
Location
Interests
Occupation

I don't want to add another AOL Instant Messenger Handle field as that would probably make that field double up in the signup form as it's already there

Any ideas?

Thanks!
Heineken77