Sandeep,
OTM supports SSO out of the box, and I recommend reading the "Enabling Single Sign On (SSO) Support" section of the OTM Admin Guide. Basically, after enabling OTM's SSO, it will look for a user ID within the HTTP header or URL, provided by a variable that you define. When this is present and populated, that user is automatically logged into OTM without password verification, effectively bypassing the login screen. This does require a custom element for each OTM user in your SSO solution's LDAP repository, though, which maps their SSO user ID to an OTM-specific user ID.
Here's a post which provides some relevant data:
http://www.otmfaq.com/forums/f25/otm-ldap-oid-952/ (OTM and LDAP (OID))
I've head that OTM will natively support the Oracle Identity Manager in a later version, don't know when it will be available.
I hope this helps!
--Chris