Order By With Function

I am converting a Sybase system to SQL 2000 and am trying to convert the following:

declare actCurs cursor for
select TRIP_CID,cKey,AH_Ts,AH_ActivityCode,AH_LogDate,AH_ RMiles,AH_ActivData
from V_TRIP_ACTIVITIES_DRLOG
where TRIP_CID in(select TRIP_CID
from t_NewDriverLogs
where DriverID=drID
and AdjBeginDate=begDate)
and AH_LogDate=begDate
and AH_ActivityCode in ('AMB','AME','ADLS','ADRJ','ADRL','ADEP' ,'ALO',
'AST','AOPH','ANOC','AKEY','AEQC','ACG', 'AENDH',
'AINS')
order by AH_Ts,F_DrLogGetDriverJoinTs(drID, TRIP_CID, cKey), cKey;

The problem is the function in the order by statement. The function is based on a different view.
Here is the code for the function:

DECLARE @joinTs DateTime,
@tmpCKey Integer

SELECT @tmpCKey = Max(cKey)
FROM V_A_DRIVER_JOIN
WHERE TRIP_CID = @tripID
AND cKey <= @curCKey
AND ADRJ_DriverID = @drID

IF @tmpCKey IS Null
SELECT @joinTs = AH_Ts
FROM V_TRIP_ACTIVITY_HEADER
WHERE TRIP_CID = @tripID AND cKey = @curCKey
ELSE
SELECT @joinTs = AH_Ts
FROM V_TRIP_ACTIVITY_HEADER
WHERE TRIP_CID = @tripID
AND cKey = @tmpCKey

RETURN(@joinTs)

If anyone can suggest a way to convert this function to be used for the order by logic I would appreciate it.

Thanks in advance.