from my point of view, the answer would be similar.
You add those resources that should have access to requests of a certain type to one security group, those of another in another security group and use tokens for the user access to request types.
It doesn't really matter what organizational department, user- or resource group they belong to. Important is that you set up a security group for those resources that should be able to access a certain request types request and give access grants to the security group depending on what you would want to have them do.
So say you have Department xyz and two different groups that use different request types.
Create Dep_xyz_group_1 and Dep_xyz_group_2 and give them access grants depending on the need. Allow on group access to one RT and the other to a different one.
you need to give the access grants necessary for the security groups first.
then you access the project request type in question and in the user access tab, you use the security group token to allow access for the relevant security group to the project request type.
You can also access the document management site on http://support.openview.hp.com and get manuals of all shades for the basics of PPM but if you are really NEW to the product, you might want to consider a base training course before you start getting lost... :-)