Shouldnt be an issue.. Is it just not going into 4low? Whats happening? Have you looked at the shift pattern for the 242 and tried to follow its path? Back when i did the swap in my zj from 249 to 242, i ended up getting like 3 different shifter tabs, for lack of a better word.. To mate to my stock linkage and get all shift settings. This tab is what actually connects the linkage to the tcase. It may just be orientated the wrong way too. Its about an inch wide 3 long 1/4" thick.. And has a small rectangle punched out to mate to the tcase.
You can pop this off and shift it with some vice grips (bin der don dat)- but be sure to have the ebrake set with the yeep in N- and just be safe about it of course.
I even cut the 249 one (or one of em) to reorintate it until i found the right one.
Ive yet to get one of these:
http://www.boostwerksengineering.com/242-HD-Shift-Linkage-V20_p_27.html
But want one just to beable to fine tune it. A friend has one installed and shifting is butter. You can get the little emblem on the shifter at a jy.