make fields allready preset with random text?

make fields allready preset with random text?

I have a site, im expecting a few hundred colleagues to sign up, they have the chioce to pick a user name and email adress of their choice, but to speed things up a bit I would like set preset usernames and emails in the fields so the user just has to press the enter button.

So for example, my 2 fields will be filled with something like
Username: [mysitename]User[randomnumber]
Email: [randomnumber]@mysite.com

where my site name is the actual name of the site, and the random number will be different on every visit.

is this possible?

Thanks ofr any advice