Code report section's (where the page number is placed) format event:
If Me.[Page] Mod 2 = 0 Then ' it's even
[ControlName].Left = 0
Else
[ControlName].Left = 7*1440 ' it's odd
End If
For even pages it's at the left margin, for odd pages it's 7 inches
from the margin.
Change the values as wanted.
All measurements are in Twips, 1440 per inch.
Make sure you have left room for the control at both sides of the
report.