Yes you do need to modify the dairings.. The same company makes a set for your generation as mine I found a set at this place and this is the set for your bike: http://www.twistedthrottle.com/trade/productview/2362/90/ They also sell a replacement water bottle as you will have to use a smaller waterbottle resovior to mount the sliders it's an extra 35 bucks...
I purchased frame sliders from R&G racing. it's an English company.. the kit comes with the replacement water bottle. I believe they have the size for the '98. and yes, you have to cut the fairing.