Hello Vidar
yes sir you can do that, but you need to edit the xml (php code)
from line 60 you have this
you need to change it for this
here from Paypal what the 3 new variables are doing
a3 - amount to be invoiced each recurrence
t3 - time period (D=days, W=weeks, M=months, Y=years)
p3 - number of time periods between each recurrence
For the example above, the variables would be:
x amount (a3) every 1 (p3) month (t3)
I didn;t test it but I'm pretty sure your are very close with that
Thanks