you not taking your customer's details, so you have the option of complying with Google or complying
with your own policy.

You must have MV_PAYMENT_MODE set in products/variable.txt to either your standard payment processor
or to 'googlecheckout'; though you may instead set this in catalog.cfg rather than variable txt as:
Variable MV_PAYMENT_MODE googlecheckout

Within the 'credit_card' section of etc/profiles.order leave
"MV_PAYMENT_MODE" 
as set and add
&set=psp __MV_PAYMENT_PSP__
&set=mv_payment_route authorizenet
(or your preferred gateway) as the last entries in the section.

and then add

&set=psp Paypal
&set=mv_payment_route paypalexpress
&final = yes
&setcheck = payment_method paypalexpress
__END__
or, if you want to use Paypal as a 'Buy now' button without taking any \
 customer details, then omit the
__COMMON_ORDER_PROFILE__ and the two 'email=...' lines above. 

Within the 'credit_card' section of etc/profiles.order leave "MV_PAYMENT_MODE" as set,
and add
&set=psp __MV_PAYMENT_PSP__
&set=mv_payment_route authorizenet
(or your preferred gateway instead of authorizenet) as the last entries in the section.

and then add