How to set up s3 using roles?

Hi,

I followed Jeffs's series on setting up laravel blog and was exploring using s3 to store my uploaded images there rather than public folder and had started following some tutorials where they create the bucket and then create an IAM user however one caveat is I am using aws learner lab as part of my university and they restrict creating users but folk have said you can still make it work using 'roles' ?

Any pointers would be appreciated :)