Or a 90-minute CD-R. 99-minute CD-Rs are quite hard to get now - the only two companies I know that ever sold them were Infiniti and Hi-Space, and I believe both have now discontinued their ranges. However, TDK still make 90-minute CD-Rs, so you might have better luck getting hold of those.
Oh yeah, and let's not forget - do 90/99-minute CD-Rs actually work on DCs? I asked that question a long time ago on some other forums I frequent, but only about two people were able to give me an answer. Both said "no", but I don't believe either was absolutely sure, so provided you can get either of those types of CD-R easily (and cheaply) enough, it's worth a try.