Mobile and portable device RF exposure and equipment authorization requirements are found in 47 CFR Sections 1.1307, 2.1091, and 2.1093.
Attachment 447498 D01 General RF Exposure Guidance v05r02 provides guidance pertaining to RF exposure requirements for mobile and portable device equipment authorizations.
Attachment 447498 D02 SAR Procedures for Dongle Xmtr v02 provides guidance for SAR testing of USB dongle transmitters.
Attachment 447498 D03 Supplement C Cross-Reference provides a cross-reference between the discontinued OET Bulletin 65 Supplement C-0101 and the applicable KDB publications.
A spreadsheet for Mobile Multi-transmitter MPE Estimation [XLS] for estimating MPE limits for multiple antennas is available at: http://www.fcc.gov/oet/ea/presentations/files/oct05/MPE-mobile.xls