Yes,
You are correct....According to the SRND. It looks like you cant do G729 on hardware IOS MTP.
Why dont you want to use G711 MTP?
The link below and excerpts from SRND
http://www.cisco.com/en/US/docs/voice_ip_comm/cucm/srnd/7x/media.html#wp1058085
Hardware MTP (Cisco NM-HDV2, NM-HD-1V/2V/2VE, 2800 and 3800 Series Routers)
•
This hardware uses the PVDM-2 modules for providing DSPs.
•Each DSP can provide 16 G.711 mu-law or a-law MTP sessions or six G.729 or G.729b MTP sessions.
Hardware MTP (Cisco 2900 and 3900 Series Routers with PVDM3)
•These routers use the PVDM3 DSPs natively on the motherboards or PVDM2 with an adaptor on the motherboard or on service modules.
•The capacity of each DSP type varies from 16 G.711 a-law or mu-law sessions for the PVDM3-16 to 256 G.711 sessions for the PVDM3-256.
Hardware MTP (Cisco WS-SVC-CMM-ACT)
•This module has four DSPs that may be configured individually.
•Each DSP can support 128 G.711 mu-law or a-law MTP sessions.
Hardware MTP (Catalyst WS-X6608-T1 and WS-X6608-E1)
•Codec support is G.711 mu-law or a-law, G.729 or G.729b.
•Configuration is done at the port level. Eight ports are available per module.
•Each port configured as an MTP resources provides 24 sessions.
Note You cannot configure G.729 or G.729b codecs when configuring hardware MTP resources in Cisco IOS. However, Unified CM can use hardware transcoding resources as MTPs if all other MTP resources are exhausted or otherwise unavailable
