Unfortunately, the Migration Assistant will not allow you to "pick and choose" individual files. It will basically have three choices:
- Restore the entire drive
- Restore applications
- Restore files
Another option would be to use Recovery Mode. Note: Instead of using this mode to restore files to your MBP's internal drive, I suggest that you use an external USB drive. This will make more sense at the last step.
If your MBP has an Intel CPU:
- Boot up in Recovery Mode.
- Select OS X or macOS Utilities
- Select "Restore From Time Machine Backup"
- Select the Time Capsule as the Backup Source.
- Select the latest backup of the iMac that you want to restore from.
- Choose the external drive for the destination that you want the backup restore to.
This may take awhile to complete. The end result is you will have all of the data files from your iMac on this external drive that you can now "pick and choose" from to restore.