Try creating a variable in two lines, then set the list to the variable
Make sure you add the second line to the existing variable. e.g.

lcVar = "ReallyReallyReallyReallyReallyReallyLongString1"
lcVar = lcVar + "ReallyReallyReallyReallyReallyReallyLongString2"

>The UpdatableFieldList property seems to have a limit as to how long the string can be. How can I work around this. I have tried two UpdatableFieldList lines of code but it only uses the last one. Please help.