How to obtain a new XenServer license using only the command line

In XenServer 6.0, this can be done with the vm-memory-limits-set command:

[root@localhost 1274]# xe help vm-memory-limits-set
command name            : vm-memory-limits-set
        reqd params     : static-min, static-max, dynamic-min, dynamic-max
        optional params : <vm-selectors>
        description     : Configure the memory limits of a VM. The simplest way to select the VM on which the operation is to be performed is by supplying the argument 'vm=<name or uuid>'. VMs can also be specified by filtering the full list of VMs on the values of fields. For example, specifying 'power-state=halted' will select all VMs whose power-state field is equal to 'halted'. Where multiple VMs are matching, the option '--multiple' must be specified to perform the operation. The full list of fields that can be matched can be obtained by the command 'xe vm-list params=all'. If no parameters to select VMs are given, the operation will be performed on all VMs.

Assuming the VM is powered down, here is an example of actually using it:

[root@localhost 1274]# xe vm-list name-label=Local-PerformanceVM params=all |grep memory
                 memory-actual ( RO): 0
                 memory-target ( RO): <expensive field>
               memory-overhead ( RO): 4194304
             memory-static-max ( RW): 268435456
            memory-dynamic-max ( RW): 268435456
            memory-dynamic-min ( RW): 268435456
             memory-static-min ( RW): 16777216
               recommendations ( RO): <restrictions><restriction field="memory-static-max" max="34359738368" /><restriction field="vcpus-max" max="8" /><restriction property="number-of-vbds" max="7" /><restriction property="number-of-vifs" max="7" /></restrictions>
                        memory (MRO):
[root@localhost 1274]# xe vm-memory-limits-set dynamic-max=300000000 dynamic-min=300000000 static-max=300000000 static-min=16777216 name-label=Local-PerformanceVM
[root@localhost 1274]# xe vm-list name-label=Local-PerformanceVM params=all |grep memory
                 memory-actual ( RO): 0
                 memory-target ( RO): <expensive field>
               memory-overhead ( RO): 5242880
             memory-static-max ( RW): 300000000
            memory-dynamic-max ( RW): 300000000
            memory-dynamic-min ( RW): 300000000
             memory-static-min ( RW): 16777216
               recommendations ( RO): <restrictions><restriction field="memory-static-max" max="34359738368" /><restriction field="vcpus-max" max="8" /><restriction property="number-of-vbds" max="7" /><restriction property="number-of-vifs" max="7" /></restrictions>
                        memory (MRO):
[root@localhost 1274]#

I shared a folder on my windows box that contains the .iso and then tried creating a CIFS SR pointing to that network share, but even though it shows up in XenCenter once I am done creating it and see under status it says OK and Connected I can't use it.

This is the best way to do what you're trying to accomplish. You should consider posting a detailed question including whatever errors you're seeing and try to get that resolved.

I don't think XenCenter has support for using flash drives as ISO repositories (or it didn't when I worked with XenServer 5.5). If you don't mind using the command line tool (xe) for managing Xen you should be able to SSH to your XenServer host and proceed. Start by reading the XenServer 6.1.0 Administrator's Guide and XenServer 6.1.0 Virtual Machine User's Guide .