You've appartently read this, in the Individual Net policy page:
The e-mail addresses given in "From:", "Reply-To:", and "Sender:" should be your own and should be valid (= should not bounce because of invalidity). Using addresses and name space of other people without their permission is prohibited.
Fine.
Now finish your homework by reading their FAQ page. There, you'll find, among other pieces of useful imformation, this:
5.3 May I mangle my "From:" header address so that I do not get SPAM?
We recommend creating a special e-mail address for use with Usenet articles only and protecting it with suitable filtering rules. This way your regular mailbox will stay untroubled, but you can still receive mail responses to your Usenet articles.
Another option is using the Top Level Domain ".invalid" (see RFC 2606). The Top Level Domain ".invalid" is intended for construction of obviously invalid addresses like "invalid@invalid.invalid". Such addresses do not disturb and pollute regular name space and can easily be identified as invalid by both humans and machines.
Sign up or don't sign up – but don't avoid signing up because of a reason that doesn't exist.