Altered Time Rate (House rules by Morpheus Unbound)

Altered Time Rate in GURPS Supers, 2d. ed.

Ever since I created the character Fast Forward, I've been looking for rules on how to relate the superpower Altered Time Rate to the GURPS combat mechanics. While I confess I don't own all the rulebooks, I'm still frustrated that Supers doesn't offer any help.

The best official help I've found is in Mixed Doubles where the characters Streaker and Pacesetter have one level of ATR. There, SJG established the way to use ATR is to multiply the characters Speed attribute by the number of levels of ATR and calculate the number of attacks as if the character simply had a very high Speed attribute (SU78).
For example, Fast Forward has four levels of Altered Time Rate (one of which he cannot turn off). Using this ruling, his minimum Speed is 11, which gives him one action per turn. His maximum Speed is 28, which gives him four actions per turn on initiative phases 28, 22, 16, and 10.
Obviously, by the example above, you are probably thinking "but shouldn't he get five attacks per turn since he has four levels of ATR?" I agree, so my alternate suggestion is a little more complicated. First, calculate the number of actions the character gets based on his Speed attribute (SU78) and what initiative phases they would occur on. Now, multiply that Speed by the levels of ATR, keeping in mind the character takes actions on the same mulple of initiative phases.
For example, Fast Forward has four levels of Altered Time Rate, one of which he cannot turn off. His Speed is 5.5, which gives him one action per normal turn on phase 5.5. Thus, with all levels of ATR activated, he takes one action on phases 27.5, 22, 16.5, 11 and 5.5.