All you need to have is mica modem firmware version 2.7.1.0 and above to support V.110 along with V.90 etc. no need to change the mica modem hardware.
Pl. visit
http://www.cisco.com/univercd/cc/td/doc/product/access/acs_serv/5300/sw_conf/sw_ports/fwpwrn/mica/rnv110bp.htm#18454
For V.110 config and debug support on mica modems on 3600 routers, pl. visit
http://www.cisco.com/univercd/cc/td/doc/product/software/ios121/121newft/121t/121t5/dtv110dm.htm
Two modem will negotiate the best connection speed possible based on line. Now To change the connection rates between two modems, you need to tweak the modem settings using S registers. Following is the url for AT commands on mica modems
http://www.cisco.com/univercd/cc/td/doc/product/access/acs_serv/5300/sw_conf/sw_ports/at_set/atcmnds.htm
So you need to adjust S29, S30, S31, S50 and S51 accordingly.
To configure those registers, you need to create modemcap. Here is the url to create and apply the modemcap to modems.
http://www.cisco.com/warp/public/471/recc_modemcaps.html
