I meant to answer this, but wasn't at a computer to check something, then forgot it when I was. Old.

The short answer is 'kinda'. The MATH function TICKms() returns a full DWORD millisecond value that rolls over at a bit over 49 days. If you did TICKms()%1000, it will match the timestamp value...for 49 days. I'm pretty sure that after that the modulus operation will diverge from the timestamp counter, since 4294967295 % 1000 = 295 and 0 % 1000 = 0.
I'm pretty sure that with a small bit of creativity you could create a relative millisecond timer from TICKms() that could give you what you want, but no, there is currently no direct access to that timestamp value. It could easily be added to MATH, but obviously wouldn't be available until the next DmD release.