Assuming you have a room and know how to create models you can now get them to do your every bidding through aiscripted sequences. First of all, consult this list for all the models and animations you can use in a single player map:

http://www.planethalflife.com/workshop/models/ssec_docs.htm

You get them to do these animated actions through the aiscripted_sequence entity- the model will perform the action at the exact location of this entity. Always remember to keep the model about a unit above the floor:



Give your target monster that you want to perform the action a name, e.g. bob. Now give the aiscripted_sequence a name of a1, and in the target monster box type bob. Now the move to position field is quite obvious, so select how you want your monster to move to this spot before they carry out their sequence. Then you may pick an action animation for this model noted in the site above and put it in the action animation field.

Finally, you need to trigger your aiscripted_sequence entity, which you might want to do with trigger_once entities so the action is only performed once!