Here is the search definition I use to find the usages of a class as type of an attribute or parameter:
select o.ea_guid as CLASSGUID,'Operation' as CLASSTYPE,o.name as Name,p.Type as 'Type', class.name as 'Class Name'
,package.name as 'Package Name',package_p1.name as 'Package level -1',package_p2.name as 'Package level -2',package_p3.name as 'Package level -3'
from t_operation as o
join t_operationparams as p on (o.operationID = p.operationID)
join t_object as class on (o.object_id = class.object_id)
join t_package as package on (class.package_id = package.package_id)
left join t_package as package_p1 on (package_p1.package_id = package.parent_id)
left join t_package as package_p2 on (package_p2.package_id = package_p1.parent_id)
left join t_package as package_p3 on (package_p3.package_id = package_p2.parent_id)
where p.type like '<Search Term>'
union
select a.ea_guid as CLASSGUID,'Attribute' as CLASSTYPE,a.name as Name, a.Type as 'Type', class.name as 'Class Name'
,package.name as 'Package Name' ,package_p1.name as 'Package level -1',package_p2.name as 'Package level -2',package_p3.name as 'Package level -3'
from t_attribute as a
join t_object as class on (a.object_id = class.object_id)
join t_package as package on (class.package_id = package.package_id)
left join t_package as package_p1 on (package_p1.package_id = package.parent_id)
left join t_package as package_p2 on (package_p2.package_id = package_p1.parent_id)
left join t_package as package_p3 on (package_p3.package_id = package_p2.parent_id)
where a.Type like '<Search Term>'
PS. This SQL is written to the syntax of SQL Server. It will probably need some tweaking to work on a local eap (MS Access) file.