Check CO search engine. I was easily able to redeem F award (75k pp each way) from IAH to Islamabad. You need to get to BKK and then ISB. Getting to BKK can be through Europe (I am doing IAH-FRA-LHR-BKK-ISB in early Nov '11 - still trying to get the direct flight from FRA to BKK but no luck yet).

You will be looking at LH, UA, CO, LX etc. to get into Europe and then most probably TG to BKK.You can even try ANA, CO , OZ, UA to get a routing to BKK over the Pacific. There are options to do that and I am doing ISB-BKK-NRT-LAX-IAH on the way back. Note that this option would not have been available on UA but CO is much more flexible in the number of miles traveled and routing one way over the Atlantic and back over the Pacific as a R/T Award and not RTW.