The Federal Bureau of Prisons (BOP) Sick Call Request Form is the standard form inmates must fill out in order to request medical services at BOP facilities. It is pretty easy to figure out, but the forms can be hard to come by because some facilities run out of copies or make rules limiting how many an inmate can be given at one time. If you have friends or family incarcerated in the federal system then these are good to have, so you are encouraged to print off the pdf version and mail copies in whoever you would like. That is probably cheaper than having your inmate buy copy cards off the commissary.
Make sure you let them know that some BOP medical personnel will not accept more than one and might confiscate the rest if they turn in several at once. At least that was the case with Brigitte Wolverton at USP Victorville a few years ago, but she was exceptionally lazy.