can you use variables in PostgreSQL rules?

i am currently migrating a db from Oracle to Pg and in some of my
triggers i use variables, i.e. i have some thing like this:

[Oracle version]

CREATE OR REPLACE TRIGGER "USERACTION_VIEW" INSTEAD OF INSERT ON
"USERACTION_VIEW" DECLARE

UserActionID INTEGER;

UserActionDataID INTEGER;

begin

SELECT USERACTION_SQ.nextval into UserActionID FROM DUAL;

SELECT USERACTIONDATA_SQ.nextval into UserActionDataID FROM DUAL;

INSERT INTO USERACTION

(

UserActionID,

LocalID,

UserActionTypeID,

ActionDate

)

VALUES

(

UserActionID,

:new.LocalID,

:new.UserActionTypeID,

SYSDATE

);

INSERT INTO USERACTIONDATA

(

UserActionDataID,

UserActionID,

AccountID,

CourseRecordID,

CourseRecordPaymentID,

StudentID,

CourseRecordTestID,

CourseRecordLessonID

)

VALUES

(

UserActionDataID,

UserActionID,

:new.AccountID,

:new.CourseRecordID,

:new.CourseRecordPaymentID,

:new.StudentID,

:new.CourseRecordTestID,

:new.CourseRecordLessonID

);

end;

so basically i have two variables here, UserActionID and
UserActionDataID. so when i am porting to PostgreSQL i will need to make
this a rule since Pg triggers only work for tables. The problem though
is that i don't know how to use variabvles in Pg rules. Any ideas? Is it
possible at all?

Thanks.