There are no predefined bolt connectors in PrePoMax. You could model the bolts as simple solids (cylinders) or using beam elements attached to the rest of the model via coupling/rigid body constraints but the latter approach requires keyword edits because beams and coupling constraints are not yet supported in PrePoMax. So the easiest way might be to tie cylinders there. Regardless of the chosen approach, you can even model pre-load using the pre-tension section.
On the forum, you will find multiple threads discussing various way of bolt modelling in PrePoMax. For example: