I'm jumping in late, but when I translated this line, I noted the
following:
``Pave the way1 for the one who rides where the sun sets2 --- his name
being Yah3 --- and rejoice before Him.''
1. From the root s.l.l, to cast a highway. Birnbaum's ``extol''
reflects a common understanding of this word, an understanding
that dates back to the Targum's translation of Ps. 68, ``lift up a
song,'' from which this passage is taken. But in light of the
following ``the one who rides...,'' our translation of ``pave''
seems much the more likely. NRSV adds a footnote to their
translation ``lift up a song:'' ``Or cast up a highway.''
2. Aravot. The idea presumably is that God rides his chariot on
high, drawing the sun across the sky. (We have a similar
expression, ``rides off into the sunset,'' but the meaning is
quite different.) NRSV suggests, ``rides among the clouds.''
3. A dubious translation, but one that attempts to understand the
Hebrew: b'yah sh'mo, literally, in/with/etc. Yah his-name. The
Hebrew does not mean ``Yah is his name.''
The translation appears in Volume I of _My People's Prayer Book_.
"Birnbaum" is Philip Birnbaum's _HaSiddur HaShalem_. NRSV is the New
Revised Standard Version translation.