Since VMware Player doesn't allow you to change where the CD-Rom is connected to like Workstation does, you lose the ability to connect to different .iso files while the virtual machine is running.
The solution here is to create a second CD-ROM device in your .vmx file and have that device pointed to a symbolic link. This allows you to disconnect the 2nd CD-ROM, change the symbolic link, and reconnect the CD-ROM. Your new .iso gets mounted.
Here's the code to add if you have a more or less "standard" .vmx file:
Then when you need to, use this code to change the symbolic link in a terminal:
# Settings for .iso CDROM drive
ide1:1.present = "TRUE"
ide1:1.startConnected = "FALSE"
ide1:1.autodetect = "FALSE"
ide1:1.deviceType = "cdrom-image"
ide1:1.filename = "/home/user/myCD.iso"
Just change the text I have in Red with the actual location of your .iso file.
user@Ubuntu:~$ ln -s -f /media/FIRELITETWO/VMwareTools/linux.iso myCD.iso
Hope this helps!!