Hi,
Yes, LONGs can only be used on 18-series parts. Do you need to do any math etc on that 32bit variable or are you just trying to store it? If you only need to store it then simply use an array of 4 bytes. If you need math you could always take a look at Darrels N-Bit math routines which will allow you to declare variables of "any" size and do math with them.

/Henrik.