I can get rails from Dell if those are needed or I can carve some from plastic or other material. It's not that hard to make.
Drives are thankfully cheap and all one might do is read the install instructions with the drive.
If your question was to move "cd/dvd writer for a Dell Inspiron laptop" into a desktop, then you didn't write that but the adapter may cost more than the 29 to 39 buck drive for the desktop.
I have a Dell Dimension 4500 and have a cd/dvd writer for a Dell Inspiron laptop. Can I install the writer in the desktop? Do I need rails? Where do I get them?