Treat Data Differently For Positive Vs Negative #

Ok, I have a table with IP addresses stored in decimal format using both positive and negative numbers.
The way that they are stored is:
Positve
1 thru 2147483647 = 0.0.0.1 - 127.255.255.255
Negative
-2147483648 thru -1 = 128.0.0.0 - 255.255.255.255
Conversion
positive
x/2^24 . (x/2^24)/2^16 . etc . etc
negative
(x+2^32)/2^24 . ((x+2^32)/2^24)/2^16 . etc . etc

I have a script which works by using UNION and the WHERE statements are x>0 x<0

My problem is I need to use a 3rd party app to run the script (McAfee ePO). McAfee does not recognize the UNION. My question is, can I acheive the same results as the script below, without using UNION.

SELECT ReportFullPathNode.FullPathName,
cast(cast(IPSubnetMask.IP_Start as bigint)/16777216 as varchar) + '.' +
cast(cast(IPSubnetMask.IP_Start as bigint)%16777216/65536 as varchar) + '.' +
cast(cast(IPSubnetMask.IP_Start as bigint)%16777216%65536/256 as varchar) + '.' +
cast(cast(IPSubnetMask.IP_Start as bigint)%16777216%65536%256 as varchar),
cast(cast(IPSubnetMask.IP_End as bigint)/16777216 as varchar) + '.' +
cast(cast(IPSubnetMask.IP_End as bigint)%16777216/65536 as varchar) + '.' +
cast(cast(IPSubnetMask.IP_End as bigint)%16777216%65536/256 as varchar) + '.' +
cast(cast(IPSubnetMask.IP_End as bigint)%16777216%65536%256 as varchar),
cast(IPSubnetMask.LeftMostBits as varchar),
IPSubnetMask.IP_Start
FROM IPSubnetMask, ReportFullPathNode ReportFullPathNode
WHERE IPSubnetMask.IP_Start>0 and IPSubnetMask.ParentID = ReportFullPathNode.LowestNodeID
UNION ALL
SELECT ReportFullPathNode.FullPathName,
cast(cast(4294967296+IPSubnetMask.IP_Start as bigint)/16777216 as varchar) + '.' +
cast(cast(4294967296+IPSubnetMask.IP_Start as bigint)%16777216/65536 as varchar) + '.' +
cast(cast(4294967296+IPSubnetMask.IP_Start as bigint)%16777216%65536/256 as varchar) + '.' +
cast(cast(4294967296+IPSubnetMask.IP_Start as bigint)%16777216%65536%256 as varchar),
cast(cast(4294967296+IPSubnetMask.IP_End as bigint)/16777216 as varchar) + '.' +
cast(cast(4294967296+IPSubnetMask.IP_End as bigint)%16777216/65536 as varchar) + '.' +
cast(cast(4294967296+IPSubnetMask.IP_End as bigint)%16777216%65536/256 as varchar) + '.' +
cast(cast(4294967296+IPSubnetMask.IP_End as bigint)%16777216%65536%256 as varchar),
cast(IPSubnetMask.LeftMostBits as varchar),
IPSubnetMask.IP_Start+4294967296
FROM IPSubnetMask, ReportFullPathNode ReportFullPathNode
WHERE IPSubnetMask.IP_Start<0 and IPSubnetMask.ParentID = ReportFullPathNode.LowestNodeID