It probably can be done... With the right tweaking to the firmware, you can make a drive do just about anything you want, and with Vlad's skills, I'm sure that he could pull it off... BUT... at the risk of sounding like the party-pooper...
1) This is very risky. To echo some concerns that companies like Plextor and Sony have put out, what if the disc explodes? Many companies are already wary of the 52x speed. Now 55x? I wouldn't want my drive going that fast.
2) The time saved would be marginal, at best. A DVD-burner overclock from 4x to 8x saves you a lot of time--that's a good mod. A DVD-burner overclock from 12x PCAV to 16x CAV (I'm sure there will be people trying this later in the year when they come out :p) would save you only a minute or so on a full burn--that's an okayish mod. A 48x to 52x jump in speed already results in a very trivial amount of time savings (just a few seconds). A CD-burner overclock from 52x to 55x would save you even fewer seconds. Personally, I think that it would be too small a gain for the risk of #1 and also for the cost in terms of the time required to be put in by TDB to find the patch points and run tests to see if it works.
3) Do you know if the hardware can even support this? Will the motor spin that fast? Will the signal processing elements of the hardware be able to cope at such speeds? Are they even able to run at the necessary frequency for this? I have every confidence in TDB's ability to change the firmware, but if the hardware can't do it, no amount of firmware magic will change the situation.