I could be wrong, but according to this, non-Indian spouses don't seem to be eligible for OCI. May be some one with a situation same as yours and who has gone thru the process can shed some more light.
1. Who is eligible to apply?
A foreign national, who was eligible to become a citizen of India on
26.01.1950 or was a citizen of India on or at anytime after 26.01.1950
or belonged to a territory that became part of India after 15.08.1947
and his/her children and grand children, provided his/her country of
citizenship allows dual citizenship in some form or other under the
local laws, is eligible for registration as an Overseas Citizen of India
(OCI). Minor children of such person are also eligible for OCI.
However, if the applicant had ever been a citizen of Pakistan or
Bangladesh, he/she will not be eligible for OCI.
2. Who was eligible to become Citizen of India on 26.01.1950?
Any person who, or whose parents or grand-parents were born in
India as defined in the Government of India Act, 1935 (as originally
enacted), and who was ordinarily residing in any country outside India
was eligible to become citizen of India on 26.01.1950.
3. Which territories became part of India after 15.08.1947 and from
what date?
The territories which became part of India after 15.08.1947 are:
(i) Sikkim 26.04.1975
(ii) Pondicherry 16.08.1962
(iii) Dadra & Nagar Haveli 11.08.1961
(iv) Goa, Daman and Diu 20.12.1961
4. Can the spouse of the eligible person apply for OCI?
Yes, if he/she is eligible in his/her own capacity.