You are only able to place a hold on one volume from a multivolume set at a time. After you have checked out the volume in question, you will be able to place a hold on another volume from that set.
1. While logged in to the online library catalog, go to the record page for the multivolume item series on which you wish to place a hold. On the right side of the page, click on "Place hold."
2. On the next page, click on "Show more options."
3. From the new options below, check the bullet labeled "A specific item."
4. In the list that appears, click the bullet next to the specific volume you wish to place on hold (denoted with "V." then a number). Once you have selected the volume, click on "Place hold."