You could look at the CCP-EM software http://www.ccpem.ac.uk/download.php which includes CCP4 programs adapted to cryoEM (e.g. allowing input of cryoEM map).
There is a range of possibilities from rigid body fitting of components, flexible fitting or de novo building. At 4 A, you may struggle with de novo building, though of course you may have regions where the local resolution is better. There are some tutorials etc here http://www.ccpem.ac.uk/training/icknield_2017/icknield_2017.php Good luck Martyn From: CCP4 bulletin board [mailto:CCP4BB@JISCMAIL.AC.UK] On Behalf Of Natalia O Sent: 23 January 2018 20:04 To: ccp4bb Subject: [ccp4bb] building into EM map Hello, I am new to building into an EM map, and I wonder if I could get a recommendation for some standard routine for programs to use. I tried "find helixes and strands" tool in phenix, it found some secondary structure elements, however, it seems that there is more that could be done automatically. Is there any standard set of tools to use for automatic building in EM map of about 4A resolution? Thank you! -Natalia